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The atomistic description of the folding process of a structureless chain of amino acids to a functioning protein is still considered to be a challenge for computational biophysics. An in-depth understanding of protein-folding can be achieved through atomistic dynamics accounting for the solvent effects, combined with the theoretical description of conformational changes in shorter polypeptide chains. The present paper studies the folding transitions in short polypeptide chains consisting of 11 alanine residues in explicit solvent employing all-atom molecular dynamics. The multiple observed folding ↔ unfolding events of the peptide are interpreted as a dynamic process and rationalised through the analysis of the potential energy surface of the system. It is demonstrated that alanine polypeptide folding dynamics is governed by the backbone dihedral angles and involves the formation of spontaneously folded α -helices which emerge and live for ca. 1–20 picoseconds. The helical content within the polypeptide at different temperatures was quantified through a statistical mechanics approach, which showed a reasonable agreement with the results of molecular dynamics simulations and experiments performed for alanine-rich peptides. [ABSTRACT FROM AUTHOR]

Pectin lyase (PMGL) is an industrially important enzyme with widespread applications in the food, paper, and textile industries, owing to its capacity for direct degradation of highly esterified pectin. In this study, PMGL-Ba derived from Bacillus licheniformis underwent mining and heterologous expression in P. pastoris. Furthermore, diverse strategies, encompassing the optimization of expression cassette components, elevation of gene dosage, and co-expression of chaperone factors, were employed to augment PMGL-Ba production in P. pastoris. The signaling peptide OST1-pre-α-MF-pro and promoter AOX1 were finally selected as expression elements. By overexpressing the transcription factor Hac1p in conjunction with a two-copy PMGL-Ba setup, a strain yielding high PMGL-Ba production was achieved. In shake flask fermentation lasting 144 h, the total protein concentration reached 1.81 g/L, and the enzyme activity reached 1821.36 U/mL. For further scale up production, high-density fermentation transpired in a 5 L fermenter for 72 h. Remarkably, the total protein concentration increased to 12.49 g/L, and the enzyme activity reached an impressive 12668.12 U/mL. The successful heterologous and efficient expression of PMGL-Ba not only furnishes a valuable biological enzyme for industrial applications but also contributes to cost reduction in the utilization of biological enzymes in industrial applications. [ABSTRACT FROM AUTHOR]

Objective: Lantibiotics are a family of bacterial antimicrobial peptides synthesized by ribosomes, that undergo post-translational modification to form lanthionine (Lan) and methyllanthionine (MeLan) residues. Lantibiotics are currently considered promising agents for combating antibiotic-resistant bacterial infections. This paper presents a biotechnological method for obtaining two components of the lantibiotic lichenicidin from Bacillus licheniformis B-511, Lchα and Lchβ. Such a system has the potential to facilitate the production of not only lichenicidin, but also other lantibiotics, including two-component ones, and also to enable the study of their biosynthesis and the activity and substrate specificity of modifying enzymes. Methods: The developed system is based on heterologous coexpression of the genes of Lchα and Lchβ precursors with the genes of their corresponding modifying enzymes in the cytoplasm of Escherichia coli BL21(DE3). Subsequent steps included immobilized metal affinity chromatography of the His-tagged hybrid peptide under denaturing conditions, cyanogen bromide cleavage in acidic medium, and final purification using reverse-phase HPLC. Results and Discussion: The system was employed for the expression and purification of lantibiotics, resulting in the successful isolation of the β-component of lichenicidin in high yield (approximately 4 mg/L of culture). This purified beta component exhibited structural and functional characteristics comparable to its natural counterpart, which was purified from the natural producer. However, the yield of the mature α-component of lichenicidin in such a system was significantly lower. Conclusions: The work presents a biotechnological method for obtaining recombinant two-component lantibiotic lichenicidin, which has proven to be particularly effective in the case of Lchβ. The developed method can also be applied to the production of other promising lantibiotics and their further research. [ABSTRACT FROM AUTHOR]

The sensitivity of localized surface plasmon resonance (LSPR) of metal nanostructures to adsorbates lends itself to a powerful class of label-free biosensors. Optical properties of plasmonic nanostructures are dependent on the geometrical features and the local dielectric environment. The exponential decay of the sensitivity from the surface of the plasmonic nanotransducer calls for the careful consideration in its design with particular attention to the size of the recognition and analyte layers. In this study, we demonstrate that short peptides as biorecognition elements (BRE) compared to larger antibodies as target capture agents offer several advantages. Using a bioplasmonic paper device (BPD), we demonstrate the selective and sensitive detection of the cardiac biomarker troponin I (cTnI). The smaller sized peptide provides higher sensitivity and a lower detection limit using a BPD. Furthermore, the excellent shelf-life and thermal stability of peptide-based LSPR sensors, which precludes the need for special storage conditions, makes it ideal for use in resource-limited settings. [ABSTRACT FROM AUTHOR]

The need for sensitive, robust, portable, and inexpensive biosensing platforms is of significant interest in clinical applications for disease diagnosis and treatment monitoring at the point-of-care (POC) settings. Rapid, accurate POC diagnostic assays play a crucial role in developing countries, where there are limited laboratory infrastructure, trained personnel, and financial support. However, current diagnostic assays commonly require long assay time, sophisticated infrastructure and expensive reagents that are not compatible with resource-constrained settings. Although paper and flexible material-based platform technologies provide alternative approaches to develop POC diagnostic assays for broad applications in medicine, they have technical challenges integrating to different detection modalities. Here, we address the limited capability of current paper and flexible material-based platforms by integrating cellulose paper and flexible polyester films as diagnostic biosensing materials with various detection modalities through the development and validation of new widely applicable electrical and optical sensing mechanisms using antibodies and peptides. By incorporating these different detection modalities, we present selective and accurate capture and detection of multiple biotargets including viruses (Human Immunodeficieny Virus-1), bacteria (Escherichia coli and Staphylococcus aureus), and cells (CD4+ T lymphocytes) from fingerprick volume equivalent of multiple biological specimens such as whole blood, plasma, and peritoneal dialysis effluent with clinically relevant detection and sensitivity. [ABSTRACT FROM AUTHOR]

Cell-adhesive factors mediate adhesion of cells to substrates via peptide motifs such as the Arg–Gly–Asp (RGD) sequence. With the onset of sustainability issues, there is a pressing need to find alternatives to animal-derived cell-adhesive factors, especially for cell-cultivated food applications. In this paper, we show how data mining can be a powerful approach toward identifying fungal-derived cell-adhesive proteins and present a method to isolate and utilize these proteins as extracellular matrices (ECM) to support cell adhesion and culture in 3D. Screening of a protein database for fungal and plant proteins uncovered that ~5.5% of the unique reported proteins contain RGD sequences. A plot of fungi species vs RGD percentage revealed that 98% of the species exhibited an RGD percentage > = 1%. We observed the formation of protein particles in crude extracts isolated from basidiomycete fungi, which could be correlated to their stability towards particle aggregation at different temperatures. These protein particles were incorporated in 3D fiber matrices encapsulating mouse myoblast cells, showing a positive effect on cell alignment. We demonstrated a cell traction stress on the protein particles (from Flammulina velutipes) that was comparable to cells on fibronectin. A snapshot of the RGD-containing proteins in the fungal extracts was obtained by combining SDS-PAGE and mass spectrometry of the peptide fragments obtained by enzymatic cleavage. Therefore, a sustainable source of cell-adhesive proteins is widely available in the fungi kingdom. A method has been developed to identify candidate species and produce cell-adhesive matrices, applicable to the cell-cultivated food and healthcare industries. [ABSTRACT FROM AUTHOR]

PK34 is a D29 mycobacteriophage-derived anti-microbial peptide (AMP) with anti-Mycobacterium tuberculosis activity. It is expected to become an auxiliary drug for the treatment of M. tuberculosis infection, or as a template for the development of anti-M. tuberculosis drugs. The focus of this paper is to obtain recombinant PK34 by a novel method of prokaryotic expression and purification by affinity chromatography. The minimum inhibitory concentration (MIC) of recombinant PK34 was better than that of synthetic PK34 as measured by the microplate-based Alamar Blue assay (MABA). In order to further compare the different anti-bacterial effects of PK34 obtained by the two methods on M. tuberculosis, the bacterial changes after drug incubation were observed at the microscopic level by transmission electron microscopy (TEM). In order to apply PK34 to clinical treatment earlier in the future, this paper tested the maximum non-toxic concentration of recombinant PK34 to the two most studied immune cells, RAW264.7 and THP-1, through cytotoxicity experiments. The maximum non-toxic concentration was the same as the MIC of recombinant PK34 to M. tuberculosis H37Rv, and both were 12.5 μg/mL. The monoclonal antibodies against PK34 and their hybridoma cell lines were prepared using recombinant PK34 as the antigen. Next, we obtained the gene sequence of the monoclonal antibody, which was prepared for the basic research of PK34 in M. tuberculosis treatment. In addition, the possible molecular docking mode between PK34 and trehalose-6,6-dimycolate (TDM) was predicted by AI simulation. To sum up, this paper provides a new idea for the birth of more new AMPs of the same type as PK34 in the future. Key points: • Design and prepare a novel recombinant PK34 anti-microbial peptide. • Recombinant PK34 has higher purity and anti-bacterial activity than synthetic PK34. • The monoclonal antibody against recombinant PK34 was prepared and sequenced. [ABSTRACT FROM AUTHOR]

CD47/SIRPα pathway is a new breakthrough in the field of tumor immunity after PD-1/PD-L1. While current monoclonal antibody therapies targeting CD47/SIRPα have demonstrated some anti-tumor effectiveness, there are several inherent limitations associated with these formulations. In the paper, we developed a predictive model that combines next-generation phage display (NGPD) and traditional machine learning methods to distinguish CD47 binding peptides. First, we utilized NGPD biopanning technology to screen CD47 binding peptides. Second, ten traditional machine learning methods based on multiple peptide descriptors and three deep learning methods were used to build computational models for identifying CD47 binding peptides. Finally, we proposed an integrated model based on support vector machine. During the five-fold cross-validation, the integrated predictor demonstrated specificity, accuracy, and sensitivity of 0.755, 0.764, and 0.772, respectively. Furthermore, an online bioinformatics tool called CD47Binder has been developed for the integrated predictor. This tool is readily accessible on http://i.uestc.edu.cn/CD47Binder/cgi-bin/CD47Binder.pl. [ABSTRACT FROM AUTHOR]

Database peptide search is the primary computational technique for identifying peptides from the mass spectrometry (MS) data. Graphical Processing Units (GPU) computing is now ubiquitous in the current-generation of high-performance computing (HPC) systems, yet its application in the database peptide search domain remains limited. Part of the reason is the use of sub-optimal algorithms in the existing GPU-accelerated methods resulting in significantly inefficient hardware utilization. In this paper, we design and implement a new-age CPU-GPU HPC framework, called GiCOPS, for efficient and complete GPU-acceleration of the modern database peptide search algorithms on supercomputers. Our experimentation shows that the GiCOPS exhibits between 1.2 to 5 × speed improvement over its CPU-only predecessor, HiCOPS, and over 10 × improvement over several existing GPU-based database search algorithms for sufficiently large experiment sizes. We further assess and optimize the performance of our framework using the Roofline Model and report near-optimal results for several metrics including computations per second, occupancy rate, memory workload, branch efficiency and shared memory performance. Finally, the CPU-GPU methods and optimizations proposed in our work for complex integer- and memory-bounded algorithmic pipelines can also be extended to accelerate the existing and future peptide identification algorithms. GiCOPS is now integrated with our umbrella HPC framework HiCOPS and is available at: https://github.com/pcdslab/gicops. [ABSTRACT FROM AUTHOR]

Interlayer spray is proposed as a convenient ionization source for direct analysis by mass spectrometry. Two slices of non-absorbent substrate hold the liquid sample to form a sandwich structure. By applying a high voltage to the sample, spray is generated at the tip of the substrate. The sampling procedure can be operated easily in an open condition and the spray is processed in a semi-enclosed condition, which leads to a relatively stable process. An ultralow amount (<2 μL) of the liquid sample can be analyzed without dilution, which ensures that the natural concentration and properties of the target are maintained. Less influence from the substrate is achieved compared with the spray methods based on porous absorbent materials, which results in a sensitivity enhancement of large molecule samples. It is demonstrated that the interlayer spray is applicable for the analysis of various compounds, including therapeutic drugs, peptides, and proteins. Good linearity can be obtained at a concentration as low as 50 ng/mL in the quantitative analysis for imatinib. We also show the ability to identify the chemical residuals on surfaces with high sensitivity by the 'wipe-spray' method, which is useful for the fast screening of illicit substances. Interlayer spray working with mass spectrometry provides a promising method for direct analysis in an ambient environment. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Context: The paper considers the features of the structure and dipole moments of several amino acids and their dipeptides which play an important role in the formation of the peptide nanotubes based on them. The influence of the features of their chirality (left L and right D) and the alpha-helix conformations of amino acids are taken into account. In particular, amino acids with aromatic rings, such as phenylalanine (Phe/F), and branched-chain amino acids (BCAAs)—leucine (Leu/L) and isoleucine (Ile/I)—as well as corresponding dipeptides (diphenylalanine (FF), dileucine (LL), and diisoleucine (II)) are considered. The main features and properties of these dipeptide structures and peptide nanotubes (PNTs), based on them, are investigated using computational molecular modeling and quantum-chemical semi-empirical calculations. Their polar, piezoelectric, and photoelectronic properties and features are studied in detail. The results of calculations of dipole moments and polarization, as well as piezoelectric coefficients and band gap width, for different types of helical peptide nanotubes are presented. The calculated values of the chirality indices of various nanotubes are given, depending on the chirality of the initial dipeptides—the results obtained are consistent with the law of changes in the type of chirality as the hierarchy of molecular structures becomes more complex. The influence of water molecules in the internal cavity of nanotubes on their physical properties is estimated. A comparison of the results of these calculations by various computational methods with the available experimental data is presented and discussed. Method: The main tool for molecular modeling of all studied nanostructures in this work was the HyperChem 8.01 software package. The main approach used here is the Hartree–Fock (HF) self-consistent field (SCF) with various quantum-chemical semi-empirical methods (AM1, PM3, RM1) in the restricted Hartree–Fock (RHF) and in the unrestricted Hartree–Fock (UHF) approximations. Optimization of molecular systems and the search for their optimal geometry is carried out in this work using the Polak–Ribeire algorithm (conjugate gradient method), which determines the optimized geometry at the point of their minimum total energy. For such optimized structures, dipole moments D and electronic energy levels (such as EHOMO and ELUMO), as well as the band gap Eg = ELUMO − EHOMO, were then calculated. For each optimized molecular structure, the volume was calculated using the QSAR program implemented also in the HyperChem software package. [ABSTRACT FROM AUTHOR]

Peptide-based therapeutics have gained attention as promising therapeutic modalities, however, their prevalent drawback is poor circulation half-life in vivo. In this paper, we report the selection of albumin-binding macrocyclic peptides from genetically encoded libraries of peptides modified by perfluoroaryl-cysteine SNAr chemistry, with decafluoro-diphenylsulfone (DFS). Testing of the binding of the selected peptides to albumin identified SICRFFC as the lead sequence. We replaced DFS with isosteric pentafluorophenyl sulfide (PFS) and the PFS-SICRFFCGG exhibited KD = 4–6 µM towards human serum albumin. When injected in mice, the concentration of the PFS-SICRFFCGG in plasma was indistinguishable from the reference peptide, SA-21. More importantly, a conjugate of PFS-SICRFFCGG and peptide apelin-17 analogue (N3-PEG6-NMe17A2) showed retention in circulation similar to SA-21; in contrast, apelin-17 analogue was cleared from the circulation after 2 min. The PFS-SICRFFC is the smallest known peptide macrocycle with a significant affinity for human albumin and substantial in vivo circulation half-life. It is a productive starting point for future development of compact macrocycles with extended half-life in vivo. Peptide-based therapeutics are promising therapeutic modalities, however, their prevalent drawback is poor circulation half-life in vivo. Here, the authors report the selection of albumin-binding macrocyclic peptides from genetically encoded libraries of peptides modified by perfluoroaryl-cysteine chemistry, with decafluoro-diphenylsulfone. [ABSTRACT FROM AUTHOR]

Insufficient research on the material basis and functional product development of horse bones has led to the waste of resources. This paper, as the by-product of horse meat bone marrow was the object, aimed to discover the flavor and antioxidant activity of novel collagen peptides. Two peptides, HBMP-1-1 and HBMP-2-1, were isolated and purified from horse bone marrow collagen protein (HBMP) hydrolysates. The combination of spectroscopic and chromatographic methods including SDS-PAGE, UV, FT-IR, CD, and SEM identified the structures of the peptides. The amino acid composition, flavor characteristics, and antioxidant activity were also evaluated. SDS-PAGE analysis showed that the molecular weight of the two peptides was concentrated under 4.1 kDa. The total amino acid contents of the HBMP-1-1 was up to 570.779 mg/g. Leucine, alanine, and glutamicacid were the predominant amino acids in HBMP-1-1 with high nutritional value, and it contained 10.07% β-folding, 46.39% β-turn, and 43.54% random coil structure. The peptide sequences IDDPTDSKPE, LNGKLTGM, ELDEGYVPK, AFQEDPDKF, and FVGKVVDPTQK with molecular weights of 1116.51, 833.45, 1049.51, 1096.49, and 1217.69 Da were detected using LC-MS/MS. The results of the antioxidant activity test showed that separation and purification significantly improved the bioactivity of the protein. The half-inhibition rate of HBMP-1-1 against DPPH, ABTS, and hydroxyl radicals were 0.054, 0.050, and 0.137 mg/mL, respectively. This article provides a scientific basis for clarifying the material basis of horse bone marrow collagen peptides. Also, it provides new approaches and ideas for exploring efficient and safe bone-derived lead compounds and products. [ABSTRACT FROM AUTHOR]

Background: About 15% to one third of migraineurs experience aura symptoms. Aura is a reversible focal neurological phenomenon involving visual, sensory, speech, and motor symptoms that usually precede migraine pain. Monoclonal antibodies against calcitonin-related peptide (anti- CGRP mAbs) are effective in preventing chronic and episodic migraine, but little is known about their effectiveness on specifically preventing migraine with aura. Methods: This is a pilot prospective observational cohort study, aiming at evaluating the effectiveness and safety of Erenumab, Fremanezumab or Galcanezumab for the treatment of migraine aura. We enrolled 14 patients at the Headache Centre of University Federico II of Naples. Duration of follow-up was 12 months. We assessed mean monthly days with aura symptoms, with or without subsequent headache, as well as mean monthly days with headache and mean monthly MIDAS score, by reviewing standardized paper patient headache diaries every three months. Results: A significant decrease in mean monthly aura days was observed throughout the observation period (median baseline: 13, interquartile range: 4–16; after 12 months: 1, interquartile range: 0–3, p < 0.001). We observed a statistically significant decrease in mean monthly headache days as well (median baseline 21, interquartile range: 16–30; after 12 months: 5, interquartile range: 4–7, p < 0.001). During the 12-month treatment period, none of the 14 patients reported mild or serious adverse events. Conclusion: Our findings suggest that anti-CGRP mAbs are highly effective in migraine with aura, both in reducing mean monthly aura days and mean monthly days with headache. [ABSTRACT FROM AUTHOR]

Context: The inhibitory effect of asparagine (Asn) and its derivatives on iron (Fe) corrosion was studied by performing density functional theory (DFT) calculations. In this paper, the global and local reactivity descriptors of Asn in the protonated and neutral forms were evaluated. Also, the changes in reactivity were investigated when dipeptides were combined with Asn. Due to the increase in the reaction centers within their molecular structure, there was an enhancement in the inhibitory effect of these dipeptides. Moreover, the adsorption energies (Eads) and the adsorption configurations of Asn and small peptides (SPs) with most stability were determined on the surface of Fe(111). It was found that dipeptides had a chemical adsorption on these substrates. In the protonated forms, there was an enhancement in the absolute values of Eads between the inhibitors and the Fe(111) surfaces. Peptides were more likely to be adsorbed on the Fe surfaces, showing the great inhibitory effect of these moieties. The results of the current research demonstrate the possibility of utilizing SPs as efficient "green" corrosion inhibitors. Methods: DFT computations were undertaken by employing the BIOVIA Material Studio with B3LYP-D3 functional and 6–31 + G* basis set. The theoretical evaluation of the inhibitory effect of asparagine (Asn) dipeptides, and the potential analysis of small peptides to protect against the corrosion of Fe, was done. [ABSTRACT FROM AUTHOR]

Auxin efflux through plasma-membrane-integral PIN-FORMED (PIN) carriers is essential for plant tissue organization and tightly regulated. For instance, a molecular rheostat critically controls PIN-mediated auxin transport in developing protophloem sieve elements of Arabidopsis roots. Plasma-membrane-association of the rheostat proteins, BREVIS RADIX (BRX) and PROTEIN KINASE ASSOCIATED WITH BRX (PAX), is reinforced by interaction with PHOSPHATIDYLINOSITOL-4-PHOSPHATE-5-KINASE (PIP5K). Genetic evidence suggests that BRX dampens autocrine signaling of CLAVATA3/EMBRYO SURROUNDING REGION-RELATED 45 (CLE45) peptide via its receptor BARELY ANY MERISTEM 3 (BAM3). How excess CLE45-BAM3 signaling interferes with protophloem development and whether it does so directly or indirectly remains unclear. Here we show that rheostat polarity is independent of PIN polarity, but interdependent with PIP5K. Catalytically inactive PIP5K confers rheostat polarity without reinforcing its localization, revealing a possible PIP5K scaffolding function. Moreover, PIP5K and PAX cooperatively control local PIN abundance. We further find that CLE45-BAM3 signaling branches via RLCK-VII/PBS1-LIKE (PBL) cytoplasmic kinases to destabilize rheostat localization. Our data thus reveal antagonism between CLE45-BAM3-PBL signaling and PIP5K that converges on auxin efflux regulation through dynamic control of PAX polarity. Because second-site bam3 mutation suppresses root as well as shoot phenotypes of pip5k mutants, CLE peptide signaling likely modulates phosphoinositide-dependent processes in various developmental contexts. In this paper the authors demonstrate that auxin efflux in the phloem vascular tissue of plants is determined by antagonism between CLE peptide signaling pathways and phosphoinositide kinases. [ABSTRACT FROM AUTHOR]

Obtaining compounds with specificity for certain isoforms of ion channels is a significant problem of curent physiology and pharmacology. In a series of papers, we have shown that the α-hairpinin fold can serve as a template for the rational design of peptide ligands of potassium channels. Here, we used molecular modeling to optimize the structure of the previously obtained Tk-hefu-10 peptide, a selective KV1.3 channel blocker, with a half-maximal inhibitory concentration (IC50) of ≈150 nM. Molecular dynamics simulation of the Tk-hefu-10–KV1.3 complex provided information on the interaction of individual amino acid residues of the peptide and channel, and the analysis of these interactions made it possible to propose amino acid substitutions in the structure of Tk-hefu-10 to increase its affinity. Novel Tk-hefu-12 peptide is a truncated analog of Tk-hefu-10 by one residue with five substitutions; it is characterized by an IC50 value of ≈70 nM against KV1.3. In addition, there are no methionine residues in the structure of Tk-hefu-12, which makes it possible to obtain Tk-hefu peptides using cyanogen bromide. [ABSTRACT FROM AUTHOR]

The aim of the paper was to develop chitosan-coated nanoliposomes for carrying bioactive peptides derived from hydrolyzed shrimp waste (SW) with chitosan coating (concentrations of 0, 0.5 and 1% W/ V). The study involved producing SW hydrolysates using protease enzymes from Bacillus salsus bacteria, followed by investigating the physicochemical, antioxidant, and antimicrobial properties of the peptide-loaded nanoliposomes. The dispersion index ranged from 0.17 to 0.65, and the particle size varied from 500 to 685 nm. Increasing the chitosan concentration to 1% significantly increased the particle size (P < 0.05). The Zeta potential of the nanoliposomes became positive as the chitosan concentration increased, starting from − 47.73 mV and reaching + 36.40 mV. The highest encapsulation efficiency (84.67%) was observed in nanoliposomes with 1% chitosan, while uncoated liposomes had the lowest encapsulation efficiency (44%). Scanning electron microscopy (SEM) revealed that the nanoparticles exhibited homogeneous, spherical, and cluster-shaped structures with smooth surfaces. Chitosan coating enhanced the stability of the peptides in simulated stomach and intestinal environments, with higher stability observed at higher chitosan concentrations (P < 0.05). Chitosan-coated nanoliposomes exhibited higher antioxidant and antimicrobial activities compared to uncoated nanoliposomes. Increasing the chitosan concentration resulted in greater inhibition of free radicals (DPPH and ABTS free radical activities increased significantly in nanoliposomes with 1% chitosan compared to uncoated samples: 32.56–70.28% and 41.58–80.28% respectively) and enhanced antimicrobial properties (P < 0.05). In conclusion, coating hydrolyzed SW with nanoliposomes and chitosan improved the structural, physicochemical, antioxidant, and antimicrobial properties of the peptides, making them suitable for direct application in food products requiring antioxidant and antimicrobial effects. [ABSTRACT FROM AUTHOR]

Background: Endometrial receptivity (ER), a pivotal event for successful embryo implantation, refers to the capacity of endometrium to allow the adhesion of the trophectoderm of the blastocyst to endometrial cells. In this paper, we set to elucidate whether the peptides encoded by lncRNAs could influence trophoblast cells' adhesion to endometrial cells. Methods: WGCNA construction and bioinformatics were used to find out the ER-related lncRNAs with coding potential. Protein analysis was done by immunoblotting and immunofluorescence (IF) microscopy. CCK-8 and Calcein-AM/PI double staining assays were employed to evaluate cell viability. The effect of the peptide on trophoblast spheroids' adhesion to endometrial cells was evaluated. The RNA sequencing (RNA-seq) analysis was applied to identify downstream molecular processes. Results: lncRNA LINC00339 was found to be related to ER development and it had been predicted to have protein-coding potential. LINC00339 had high occupancy of ribosomes and was confirmed to encode a 49-aa peptide (named LINC00339-205-49aa). LINC00339-205-49aa could promote the attachment of JAR trophoblast spheroids to Ishikawa endometrial cells in vitro. LINC00339-205-49aa also upregulated the expression of E-cadherin in Ishikawa cells. Mechanistically, MAPK and PI3K-Akt signaling pathways were involved in the modulation of LINC00339-205-49aa, which were activated by LINC00339-205-49aa in Ishikawa cells. Conclusion: These data demonstrate that a previously uncharacterized peptide encoded by lncRNA LINC00339 has the ability to enhance JAR trophoblast spheroids' adhesion to Ishikawa endometrial cells, highlighting a new opportunity for the development of drugs to improve ER. [ABSTRACT FROM AUTHOR]

The detection of botulinum neurotoxin A (BoNT/A) endopeptidase activity by pregnancy test paper based on human chorionic gonadotropin (hCG)-functionalized peptide-modified magnetic nanoparticles (MNs) is described for the first time. HCG-functionalized SNAP-25 peptide substrate with hydrolysis recognition sites was optimally designed. HCG can be recognized by pregnancy test strips. BoNT/A light chain (BoNT-LcA) is the central part of the endopeptidase function in holotoxin, which can specifically hydrolyze SNAP-25 peptide to release the hCG-peptide probe, and the hCG-peptide probe released can be quantitatively detected by pregnancy test strips, achieving indirect determination of BoNT/A. By quantifying the T-line color intensity of test strips, the visual detection limit for BoNT-LcA is 12.5 pg/mL, and the linear range of detection for BoNT-LcA and BoNT/A holotoxin was 100 pg/mL to 1 ng/mL and 25 to 250 ng/mL. The ability of the method to quantify BoNT/A was validated in human serum samples. This method shows the potential for sensitive detecting BoNT/A and has prospects for the diagnosis and prognosis of clinical botulism. [ABSTRACT FROM AUTHOR]

Human enterokinase light chain (hEKL) cDNA sequence was designed with the help of codon optimization towards Escherichia coli codon preference and ribosome binding site design and artificially synthesized with a thioredoxin fusion tag at the N-terminal and a five his-tag peptide at the C-terminal. The synthetic hEKL gene was cloned into the pET-15 expression vector and transferred into the three different expression strains of E. coli BL21(DE3), NiCo21, and SHuffle T7 Express. Different growth and induction conditions were studied using a statistical response surface methodology (RSM). Recombinant hEKL protein was expressed at high levels in soluble form with 0.71 mM IPTG after 4 h of induction at 25 °C. Autocatalytic process cleaved TRX tag with enterokinase recognition site by the impure hEKL and yielded the mature enzyme. The target protein was then purified to homogeneity (> 95%) by affinity chromatography. The activity of hEKL was comparable to the commercial enzyme. From 1 L culture, 80 mg pure active hEKL was obtained with the specific activity of 6.25 × 102 U/mg. Three main parameters that help us to produce the enzyme in the folded and active form are the type of strain, SHuffle T7 strain, TRX and histidine fusion tags, and growth conditions including the increase of OD of induction and IPTG concentration and the decrease of induction temperature. Key points: Combining several parameters suggested in different papers in one experiment to get the active enzyme. Decreasing the temperature of induction and the amount of inducer and using a chaperone-like tag simultaneously to help the protein folding system of the bacteria. Using a statistical method (RSM) to analyze a number of treatments and prediction of the most effective ones to optimize the expression system. [ABSTRACT FROM AUTHOR]

In this paper we give the overview of our latest results on the complexation between polyelectrolytes and oppositely charged low-molar mass species, proteins, homopolymers and block copolymers. First, we review the results on the study of the interaction of polythiophene-based polycations with phosphonium and ammonium pendants and their complexation with negatively charged multivalent species followed by fluorescence quenching. We proved that multivalent solutes bind to polyelectrolyte stronger than to previously studied polythiophene, thus, allowing for their application as luminescence sensors. Secondly, we investigated the co-assembly of polyanion with double hydrophilic block copolymer composed of polycationic block and neutral hydrophilic block and followed the complex formation by quenching of fluorescence of the indicator attached to the end of polyanion chain. We discovered that the formed interpolyelectrolyte (IPEC) core of core/shell micelles remains dynamical even after equilibrium was reached thus making such systems suitable materials for targeted delivery of multivalent species. In addition, the formation of micelles with fluid cores was observed as a result of self-assembly of di- and triblock polyelectrolytes containing a hydrophobic block with low glass transition temperature and a positively charged block. We proved their ability to encapsulate and release hydrophobic species from the soft core upon dilution. Moreover, we confirmed their ability to complex with multivalent negatively charged species. The morphology of the formed complex strongly depends on ionic strength: the aggregates formed by micelles bonded at the periphery disrupt with increasing salt concentration and a part of multivalent ions releases into solution. Finally, the multilayered nanoparticles with both soft hydrophobic and IPEC layers were designed by co-assembly between core/shell micelles with a soft core and a positively charged shell, and block polyelectrolyte composed of polyanion and neutral hydrophilic blocks. We showed that the morphology of the particles and the charge of IPEC layer of such multicompartment nanostructures can be controlled by the ratio of oppositely charged monomeric units. [ABSTRACT FROM AUTHOR]

Interferences from isobaric and isomeric compounds represent a common problem in liquid chromatography coupled to mass spectrometry (LC-MS). In this paper, in-source purification and chromatographic separation were combined with the aim of identifying isobaric contamination and quantifying accurately a compound despite the presence of an isobaric co-eluted interference. This is achieved by totally fragmenting in-source the precursor ions of the isobaric interference providing then LC-pseudo-MS2 capability, which allows an accurate quantification without the need for optimizing the chromatographic conditions to separate the co-eluted interference. To illustrate this concept, mixtures of tryptic and non-tryptic peptides were used. The ratio of peak areas of the tryptic peptide and its isotopically labelled internal standard was used not only for quantification with an internal standard calibration curve but also to know (1) if an isobaric interference co-eluted with the tryptic peptide; and (2) what is the minimum cone voltage necessary to ensure the complete removal of isobaric interference. This strategy was applied to quantify the tryptic peptide of two standards with known concentrations and, intentionally contaminated with the isobaric interference. The confidence intervals of the concentrations calculated with the internal standard calibration curve were 8.0 ± 0.5 μM (prepared at 8.0 μM) and 15.7 ± 0.5 μM (prepared at 16.1 μM) that confirm the tryptic peptide can be correctly quantified by in-source purification without the need for improving the chromatographic separation from its isobaric interference. [ABSTRACT FROM AUTHOR]

Background Hepatitis C Virus (HCV) infection is one of the causal agents of liver disease burden. Six multiple antigenic peptides were synthesized including (P315, P412, and P517) plus (P1771, P2121, and P2941) to induce humoral and cellular responses, respectively against HCV infection. Aim: This paper aimed to employ computational tools to evaluate the efficacy of each peptide individually and to determine the most effective one for better vaccine development and/or immunotherapy. Methods VaxiJen web and AllerTOP servers were used for antigenicity and allergenicity prediction, respectively. The ToxinPred web server was used to investigate the peptide toxicity. Each peptide was docked with its corresponding receptors. Results No peptides were expected to be toxic. P315 and P2941 are predicted to have robust antigenic properties, lowest allergenicity, and minimal sOPEP energies. In turn, P315 (derived from gpE1) formed the highest hydrophobic bonds with the BCR and CD81 receptors that will elicit B cell function. P2941 (derived from NS5B) was shown to strongly bind to both CD4 and CD8 receptors that will elicit T cell function. Conclusion P315 successfully bound to B cell (BCR and CD81) receptors. Also, P2941 is strongly bound to T cell (CD4 and CD8) receptors. [ABSTRACT FROM AUTHOR]

The diversification of the characteristic sequences of anti-cancer peptides has imposed difficulties on research. To effectively predict new anti-cancer peptides, this paper proposes a more suitable feature grouping sequence and spatial dimension-integrated network algorithm for anti-cancer peptide sequence prediction called GRCI-Net. The main process is as follows: First, we implemented the fusion reduction of binary structure features and K-mer sparse matrix features through principal component analysis and generated a set of new features; second, we constructed a new bidirectional long- and short-term memory network. We used traditional convolution and dilated convolution to acquire features in the spatial dimension using the memory network's grouping sequence model, which is designed to better handle the diversification of anti-cancer peptide feature sequences and to fully learn the contextual information between features. Finally, we achieved the fusion of grouping sequence features and spatial dimensional integration features through two sets of dense network layers, achieved the prediction of anti-cancer peptides through the sigmoid function, and verified the approach with two public datasets, ACP740 (accuracy reached 0.8230) and ACP240 (accuracy reached 0.8750). The following is a link to the model code and datasets mentioned in this article: https://github.com/ YouHongfeng101/ACP-DL. [ABSTRACT FROM AUTHOR]

Duchenne muscular dystrophy (DMD) afflicts 1 in 5000 newborn males, leading to progressive muscle weakening and the loss of ambulation between the ages of 8 and 12. Typically, DMD patients pass away from heart failure or respiratory failure. Currently, there is no cure, though exon-skipping therapy including eteplirsen (brand name Exondys 51), a synthetic antisense oligonucleotide designed to skip exon 51 of the dystrophin gene, is considered especially promising. Applicable to approximately 14% of DMD patients, a phosphorodiamidate morpholino oligomer (PMO) antisense oligonucleotide eteplirsen received accelerated approval by the US Food and Drug Administration (FDA) in 2016. Throughout clinical trials, eteplirsen has been well tolerated by patients with no serious drug-related adverse events. The most common events observed are balance disorder, vomiting, and skin rash. Despite its safety and promise of functional benefits, eteplirsen remains controversial due to its low production of dystrophin. In addition, unmodified PMOs have limited efficacy in the heart. To address these concerns of efficacy, eteplirsen has been conjugated to a proprietary cell-penetrating peptide; the conjugate is called SRP-5051. Compared to eteplirsen, SRP-5051 aims to better prompt exon-skipping and dystrophin production but may have greater toxicity concerns. This paper reviews and discusses the available information on the efficacy, safety, and tolerability data of eteplirsen and SRP-5051 from preclinical and clinical trials. Issues faced by eteplirsen and SRP-5051, including efficacy and safety, are identified. Lastly, the current state of eteplirsen and exon-skipping therapy in general as a strategy for the treatment of DMD are discussed. [ABSTRACT FROM AUTHOR]

In this paper, four models of quantitative structure-activity relationship (QSAR) for 84 angiotensin I-converting enzyme inhibitory (ACEI) dipeptides, 169 ACEI tripeptides and 15 ACEI tetrapeptides and the total 268 peptides were established, respectively. During every modeling process, the structure of the peptides were firstly described using a set of amino acid descriptor SVHEHS proposed previously in our laboratory, then QSAR models were developed successfully by orthogonal signal correction combined with support vector machine (OSC-SVM). Furthermore, all models were validated by the reasonable statistical parameters, such as correlation coefficient (R2), cross-validated correlation coefficient (q2) and external validation coefficient (q2ext), etc. The results demonstrated that all developed QSAR models had excellent fitting accuracy and predictive ability. It could be a very promising approach for QSAR study on bioactive peptides using SVHEHS descriptor and OSC-SVM. [ABSTRACT FROM AUTHOR]

The paper is devoted to the problems of the life origin, the study of which was launched by the Academician E.M. Galimov. E.M. Galimov is a scientist with a wide range of research interests, a deep understanding of fundamental natural processes, a researcher with a remarkable intuition. Numerous considerations and discussions of one of the authors of the article, S.D. Varfolomeev with the Аcademician E.M. Galimov resulted in the formulation of a concept providing a natural-scientific explanation of the origin of life. The basic kinetic principles of the nucleation and evolution of protobiopolymeric molecules are considered. Our approach involves the processes of polymerization and selection of macromolecular structures and is based on thermocycle, which provides the thermodynamic possibility of the formation of a monomer–monomer bond and kinetic selection of structures through a choice of more statutory complexes. Kinetic modeling and analysis of obtained solutions demonstrated the possibility of exponential growth of all protopolymers of the system and the formation of possible interpolymer complexes representing the prototypes of ribosome-type cellular organelles. The possibility of the emergence of life having a fundamentally different chemical basis under nonterrestrial conditions is considered. [ABSTRACT FROM AUTHOR]

The development of preventive vaccines became the first order task in the COVID-19 pandemic caused by SARS-CoV-2. This paper reports the construction of the pVAX-RBD plasmid containing the Receptor-Binding Domain (RBD) of the S protein and a unique signal sequence 176 which promotes target protein secretion into the extracellular space thereby increasing the efficiency of humoral immune response activation. A polyglucine-spermidine conjugate (PGS) was used to deliver pVAX-RBD into the cells. The comparative immunogenicity study of the naked pVAX-RBD and pVAX-RBD enclosed in the PGS envelope showed that the latter was more efficient in inducing an immune response in the immunized mice. In particular, RBD-specific antibody titers were shown in ELISA to be no higher than 1 : 1000 in the animals from the pVAX-RBD group and 1 : 42 000, in the pVAX-RBD-PGS group. The pVAX-RBD‒PGS construct effectively induced cellular immune response. Using ELISpot, it has been demonstrated that splenocytes obtained from the immunized animals effectively produced INF-γ in response to stimulation with the S protein-derived peptide pool. The results suggest that the polyglucine-spermidine conjugate-enveloped pVAX-RBD construct may be considered as a promising DNA vaccine against COVID-19. [ABSTRACT FROM AUTHOR]

The paper summarizes data on the existence of evolutionarily fixed species balance of interactions between peptides, RNA, and DNA that provide the stability of the development and functioning of tissues and organs in ontogenesis. Identification of key structures that disturb this balance with aging can become a basis for a specific targeted effect on reversible epigenetic mechanisms of their origin. Non-coding RNAs that, in addition to the function of ribozymes and effectors of RNA interference, are capable of being translated into peptides, which can be the most convenient targets. The effect of the latter on non-coding RNAs and involvement in the same biological processes can become a basis for a complex approach in the development of new geroprotective drugs. It was suggested that peculiarities of the expression of non-coding RNAs typical for a cell type and stage of development reflect transposon activation patterns (programmed at the species level) required for setting of tissue-specific gene networks. This is caused by the formation of non-coding RNAs from transposon transcripts that are regulators of the expression of protein-coding genes in successive cell divisions. [ABSTRACT FROM AUTHOR]

Numerous novel methods to detect foodborne pathogens have been extensively developed to ensure food safety. Among the important foodborne bacteria, Bacillus cereus was identified as a pathogen of concern that causes various food illnesses, leading to interest in developing effective detection methods for this pathogen. Although a standard method based on culturing and biochemical confirmative test is available, it is time- and labor-intensive. Alternative PCR-based methods have been developed but lack high-throughput capacity and ease of use. This study, therefore, attempts to develop a robust method for B. cereus detection by leveraging the highly specific pyrrolidinyl peptide nucleic acids (PNAs) as probes for a bead array method with multiplex and high-throughput capacity. In this study, PNAs bearing prolyl-2-aminocyclopentanecarboxylic acid (ACPC) backbone with groEL, motB, and 16S rRNA sequences were covalently coupled with three sets of fluorescently barcoded beads to detect the three B. cereus genes. The developed acpcPNA-based bead array exhibited good selectivity where only signals were detectable in the presence of B. cereus, but not for other species. The sensitivity of this acpcPNA-based bead assay in detecting genomic DNA was found to be 0.038, 0.183 and 0.179 ng for groEL, motB and 16S rRNA, respectively. This performance was clearly superior to its DNA counterpart, hence confirming much stronger binding strength of acpcPNA over DNA. The robustness of the developed method was further demonstrated by testing artificially spiked milk and pickled mustard greens with minimal interference from food metrices. Hence, this proof-of-concept acpcPNA-based bead array method has been proven to serve as an effective alternative nucleic acid-based method for foodborne pathogens. [ABSTRACT FROM AUTHOR]

In this paper, we study the interaction of five immersion agents based on solutions of disaccharides (sucrose, maltose, lactose, trehalose, and cellobiose) with collagen peptide (GPH)3 as one of the main components of biological tissues using the methods of classical molecular dynamics (GROMACS), molecular docking (AutoDock Vina), and quantum chemistry (PM6 and DFT/B3LYP). As a result of complex molecular modeling, parameters such as the optical clearing potential for rat skin and the optical clearing efficiency for human skin were predicted for these agents. The reasons for the significant difference in the values of the optical clearing parameters of immersion agents belonging to the same molecular group are discussed. [ABSTRACT FROM AUTHOR]

Cell surface engineering is a rapidly developing technology of microorganism that achieves modification of cell surface function by joining external functional peptides with surface anchoring proteins, for example, Outer Member Protein (OMP). On account of these proteins possessing metal responsive motifs, they can be specifically used for metal adsorption and dissociation. To elucidate the problems caused by heavy metals and develop various technologies for their removel or recovery, various metal-binding proteins/peptides fused on microorganism cell surface have been applied as novel methods. During the past few years, bacterial cell surface display strategy has received growing attention for their availability to eliminate heavy metals. In this paper, the existing problems, progress, and suggestions for furture of the peptide displaying system are summarized. [ABSTRACT FROM AUTHOR]

Terahertz spectroscopy and density functional theory (DFT) calculations have been used to study the dipeptide l-carnosine. In this paper, we expand the range of materials described with THz measurements and DFT calculations from amino acids to dipeptides. Three clear resonances were detected in the experimental spectrum at 1.5 THz, 1.9 THz, and 2.3 THz. Additionally, we performed periodic boundary condition DFT calculations. The computational spectrum accurately reproduces the experimental one. [ABSTRACT FROM AUTHOR]

Objectives: This research paper was to investigate the influence of soybean peptides addition on viable count of lactic acid bacteria, physicochemical parameters, flavor, and sensory evaluation of yoghurt. Results: The number of fermenting strains (Streptococcus thermophilus + Lactobacillus delbrueckii subsp. bulgaricus) cells in yoghurt (stored at 4 °C for 19 days) added with 0.2% (w/v) of soybean peptides (808.34 Da) reached 1.4 times higher bacterial number than in the control group. A total of 34 volatile substances were detected in this study, while there were 22 volatiles occurred in the control group yoghurt, 30 volatiles were detected in yoghurt added with 0.2% soybean peptides. There was no significant difference in sensory evaluation (p > 0.05) between the yoghurt with and without soybean peptides. Conclusions: In our study, the addition of soybean peptides (0.2%) can be effective both in maintaining the viable bacterial count and yoghurt quality. [ABSTRACT FROM AUTHOR]

This paper presents a study of the response of FRET based DNA aptasensors in the intracellular environment. Herein, we extend previous studies of aptasensors functioning in the extracellular environment to detection of antigens in the intracellular environment. An essential step in this research is the use of a novel means of achieving the endocytosis of aptasensors. Specifically, it is demonstrated that functioning aptasensors are successfully endocytosed by functionalizing the aptasensors with endocytosis—inducing DSS peptides. [ABSTRACT FROM AUTHOR]

Plant cysteine-rich peptides (CRP) play a key role in protection of plants from pathogens and abiotic stress, in symbiosis with bacteria, and in plant development and reproduction. The composition and role of CRPs in tomato Solanum lycopersicum, one of the most important vegetable, has not been studied so far. In this paper, using two approaches, hidden Markov models and regular expressions, in silico identification of tomato CRP families was performed. A bioinformatic analysis of NCBI databases revealed 191 CRP precursors. The peptides found belong to the families of antimicrobial and signaling peptides. Among the antimicrobial peptides, defensins and defensin-like peptides, nonspecific lipid-transfer proteins, thionins, snakins, and hevein- and knottin-like peptides were found. Among signaling peptides, the peptides belonging to the RALF, Ole e 1, Ole e 6, and MEG families were discovered. In addition, peptides with new cysteine motifs were identified. All discovered CRPs are synthesized as pre- or preproproteins. The predicted mature peptides were characterized by cysteine motifs, antimicrobial activity, and domain structure. Thus, for the first time, using bioinformatic approaches, systemic data on the arsenal of CRPs in the tomato genome were obtained, which creates a basis for further functional studies of these peptides and their subsequent use in agriculture to develop new strategies for increasing tomato pathogen resistance, as well as in medicine to create next-generation drugs. [ABSTRACT FROM AUTHOR]

Background: One of the most common metabolic diseases, Type 2 Diabetes Mellitus (T2DM), is caused by a combination of two basic factors: insufficient insulin secretion by pancreatic -cells or a failure of insulin-sensitive tissues to respond adequately to insulin. The aim of this paper was to assess the diagnostic accuracy of serum nesfatin-1 in type 2 diabetes mellitus (T2DM). Methods: Sixty patients with T2DM were recruited from (Baquba Teaching Hospital) in Iraq during the period (from November 2021 - March 2022). T2DM group was classified into 30 newly diagnosis patients (without treatment) and 30 ongoing diabetic patients (with treatment) for comparison, as well 30 healthy individuals were included as a control. The ELISA Kit was used to measure serum nesfatin-1 and serum insulin, fasting serum glucose, and lipid profile test were measured through spectrophotometric, instead of HbA1c was determined using HPLC method. Results: The concentration of serum nesfatin-1 in the T2DM group was significantly lower than that of the healthy subjects (p < 0.05). There was a significant difference in the serum nestafin-1 concentrations between newly diagnosis and ongoing T2DM patients. There were substantial negative connections between serum Nesfatin-1 concentration and HOMA-IR, as well as strong negative correlations between serum nesfatin-1 and serum insulin level. The concentration of serum Nesfatin-1, on the other hand, had no significant association with the anthropometries measurements and biochemical parameters. The area under the curve was excellent (AUC = 0.827, p = 0.0001), with high diagnostic accuracy (86.2) in differentiating newly diagnosis T2DM from the healthy subject group. Conclusion: Nesfatin-1 levels in the sera of diabetic patients was shown to be lower and nesfatin-1 levels were shown to be significantly linked to newly diagnosed patients. Highlight: • Nesfatin-1 is a novel biomarker candidate in type 2 diabetes mellitus. • Nesfain-1 can be used to differentiate T2DM from healthy subject. • The nesfatin-1 change depends on the severity of diseases (disease severity depended on increased HOMA-IR) of T2DM. [ABSTRACT FROM AUTHOR]

Human neutrophil elastase (HNE) is one of a number of proteases that is receiving increased attention as a marker for inflammatory diseases and sensor-based point of care diagnostics. Integral to sensor-based detection is the transducer surface, which is the platform of the sensor's signal transmittance. Here we describe the bioactivity and related transducer surface properties of cellulose and nanocellulose matrices as peptide-cellulose fluorescent sensors. Detection sensitivity of the sensor signals for HNE levels typically found in chronic wounds is characterized. The fluorescent elastase peptide substrate, Succinamidyl-Ala-Ala-Pro-Val-amidylcoumadin (Pep) was employed in both cellulose and nanocellulose transducer surfaces evaluated for biosensor sensitivity to HNE. The cellulose transducers selected are filter paper (FP) and print cloth (PC) fabric and are comprised of processed cotton fibers. The nanocellulose transducers are the wood cellulose nanocrystals (wCNC) and the wood nanocellulose composites (wNCC). The wNCCs consist of blended quantities of nanocrystalline and microfibrillated cellulose at 66/33 and 50/50, and are characterized as thin films. The biosensor activity was in the order of wCNC-Pep > FP-Pep = NCC-Pep (50/50) > NCC-Pep (66/33) > PC-Pep. Sensor sensitivity correlated with specific surface area. A depiction of peptide substitution on nanocellulosic and cellulosic surfaces is rendered through peptide-cellulose crystallite models derived from X-ray diffraction analysis of the material, and the models discussed in light of biosensor structure activity relationships. In addition, the overall morphology, pore size and porosity of the materials are discussed for their suitability as protease sensors. [ABSTRACT FROM AUTHOR]

In eukaryotes, the origin recognition complex (ORC) faciliates the assembly of pre-replicative complex (pre-RC) at origin DNA for replication licensing. Here we show that the N-terminal intrinsically disordered region (IDR) of the yeast Orc2 subunit is crucial for this process. Removing a segment (residues 176-200) from Orc2-IDR or mutating a key isoleucine (194) significantly inhibits replication initiation across the genome. These Orc2-IDR mutants are capable of assembling the ORC-Cdc6-Cdt1-Mcm2-7 intermediate, which exhibits impaired ATP hydrolysis and fails to be convered into the subsequent Mcm2-7-ORC complex and pre-RC. These defects can be partially rescued by the Orc2-IDR peptide. Moreover, the phosphorylation of this Orc2-IDR region by S cyclin-dependent kinase blocks its binding to Mcm2-7 complex, causing a defective pre-RC assembly. Our findings provide important insights into the multifaceted roles of ORC in supporting origin licensing during the G1 phase and its regulation to restrict origin firing within the S phase. In eukaryotes, the origin recognition complex (ORC) is essential for replication licensing. Here, the authors report that a short motif within the intrinsically disordered region of the yeast Orc2 subunit plays an important role in regulating the licensing process. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD), characterized by cognitive decline, is increasingly recognized as a disorder marked by synaptic loss and dysfunction. Despite this understanding, the underlying pathophysiological mechanisms contributing to synaptic impairment remain largely unknown. In this study, we elucidate a previously undiscovered signaling pathway wherein the S-nitrosylation of the Cdk5 activator p39, a post-translational modification involving the addition of nitric oxide to protein cysteine residues, plays a crucial role in synaptic dysfunction associated with AD. Our investigation reveals heightened p39 S-nitrosylation in the brain of an amyloid precursor protein (APP)/presenilin 1 (PS1) transgenic mouse model of AD. Additionally, soluble amyloid-β oligomers (Aβ), implicated in synaptic loss in AD, induce p39 S-nitrosylation in cultured neurons. Notably, we uncover that p39 protein level is regulated by S-nitrosylation, with nitric oxide S-nitrosylating p39 at Cys265 and subsequently promoting its degradation. Furthermore, our study demonstrates that S-nitrosylation of p39 at Cys265 significantly contributes to amyloid-β (Aβ) peptide-induced dendrite retraction and spine loss. Collectively, our findings highlight S-nitrosylation of p39 as a novel aberrant redox protein modification involved in the pathogenesis of AD, suggesting its potential as a therapeutic target for the disease. This study highlights S-nitrosylation of p39, a post-translational modification in which nitric oxide is attached to free cysteine residues, as a novel aberrant redox protein modification involved in the synaptic dysfunction in Alzheimer's disease pathogenesis. [ABSTRACT FROM AUTHOR]

Collagen posttranslational processing is crucial for its proper assembly and function. Disruption of collagen processing leads to tissue development and structure disorders like osteogenesis imperfecta (OI). OI-related collagen processing machinery includes prolyl 3-hydroxylase 1 (P3H1), peptidyl-prolyl cis-trans isomerase B (PPIB), and cartilage-associated protein (CRTAP), with their structural organization and mechanism unclear. We determine cryo-EM structures of the P3H1/CRTAP/PPIB complex. The active sites of P3H1 and PPIB form a face-to-face bifunctional reaction center, indicating a coupled modification mechanism. The structure of the P3H1/CRTAP/PPIB/collagen peptide complex reveals multiple binding sites, suggesting a substrate interacting zone. Unexpectedly, a dual-ternary complex is observed, and the balance between ternary and dual-ternary states can be altered by mutations in the P3H1/PPIB active site and the addition of PPIB inhibitors. These findings provide insights into the structural basis of collagen processing by P3H1/CRTAP/PPIB and the molecular pathology of collagen-related disorders. Collagen requires complicated modifications for proper assembly. Here, the authors show the structural basis of human collagen processing by the P3H1/CRTAP/PPIB complex, revealing a 'face-to-face' catalytic site configuration, collagen binding sites, and transition between trimer and hexamer states. [ABSTRACT FROM AUTHOR]

In eukaryotes, the leading strand DNA is synthesized by Polε and the lagging strand by Polδ. These replicative polymerases have higher processivity when paired with the DNA clamp PCNA. While the structure of the yeast Polε catalytic domain has been determined, how Polε interacts with PCNA is unknown in any eukaryote, human or yeast. Here we report two cryo-EM structures of human Polε–PCNA–DNA complex, one in an incoming nucleotide bound state and the other in a nucleotide exchange state. The structures reveal an unexpected three-point interface between the Polε catalytic domain and PCNA, with the conserved PIP (PCNA interacting peptide)-motif, the unique P-domain, and the thumb domain each interacting with a different protomer of the PCNA trimer. We propose that the multi-point interface prevents other PIP-containing factors from recruiting to PCNA while PCNA functions with Polε. Comparison of the two states reveals that the finger domain pivots around the [4Fe-4S] cluster-containing tip of the P-domain to regulate nucleotide exchange and incoming nucleotide binding. In eukaryotes, the leading strand DNA polymerase Polε synthesises the DNA with higher processivity when in complex with the DNA clamp PCNA. Here, the authors report two cryo-EM structures of human Polε bound to the PCNA clamp and a DNA substate, revealing the conformational changes associated with incoming nucleotide binding. [ABSTRACT FROM AUTHOR]

Peptides are valuable for therapeutic development, with multicyclic peptides showing promise in mimicking antigen-binding potency of antibodies. However, our capability to engineer multicyclic peptide scaffolds, particularly for the construction of large combinatorial libraries, is still limited. Here, we study the interplay of disulfide pairing between three biscysteine motifs, and designed a range of triscysteine motifs with unique disulfide-directing capability for regulating the oxidative folding of multicyclic peptides. We demonstrate that incorporating these motifs into random sequences allows the design of disulfide-directed multicyclic peptide (DDMP) libraries with up to four disulfide bonds, which have been applied for the successful discovery of peptide binders with nanomolar affinity to several challenging targets. This study encourages the use of more diverse disulfide-directing motifs for creating multicyclic peptide libraries and opens an avenue for discovering functional peptides in sequence and structural space beyond existing peptide scaffolds, potentially advancing the field of peptide drug discovery. Multicyclic peptides have the potential to mimic the antigen-binding potency of the complementarity-determining regions of antibodies, enabling the development of potent peptide binders to challenging targets, but the scaffolds of multicyclic peptides are difficult to engineer. Here, the authors design a range of triscysteine motifs with disulfide-directing capability for regulating the oxidative folding of multicyclic peptides and employ them in the design of disulfide-directed multicyclic peptide libraries for discovery of potent peptide binders. [ABSTRACT FROM AUTHOR]

The inhibitor of κB (IκB) kinase (IKK) is a central regulator of NF-κB signaling. All IKK complexes contain hetero- or homodimers of the catalytic IKKβ and/or IKKα subunits. Here, we identify a YDDΦxΦ motif, which is conserved in substrates of canonical (IκBα, IκBβ) and alternative (p100) NF-κB pathways, and which mediates docking to catalytic IKK dimers. We demonstrate a quantitative correlation between docking affinity and IKK activity related to IκBα phosphorylation/degradation. Furthermore, we show that phosphorylation of the motif's conserved tyrosine, an event previously reported to promote IκBα accumulation and inhibition of NF-κB gene expression, suppresses the docking interaction. Results from integrated structural analyzes indicate that the motif binds to a groove at the IKK dimer interface. Consistently, suppression of IKK dimerization also abolishes IκBα substrate binding. Finally, we show that an optimized bivalent motif peptide inhibits NF-κB signaling. This work unveils a function for IKKα/β dimerization in substrate motif recognition. The inhibitor of kB kinase (IKK) is a central regulator of NF-kB signalling. Here the authors identify a motif conserved in substrates of canonical and alternative NF-kB pathways which mediates docking to catalytic IKK dimers: they show that phosphorylation of the conserved tyrosine suppresses the docking interaction. [ABSTRACT FROM AUTHOR]

Natural products are molecules that fulfil a range of important ecological functions. Many natural products have been exploited for pharmaceutical and agricultural applications. In contrast to many other specialised metabolites, the products of modular nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) systems can often (partially) be predicted from the DNA sequence of the biosynthetic gene clusters. This is because the biosynthetic pathways of NRPS and PKS systems adhere to consistent rulesets. These universal biosynthetic rules can be leveraged to generate biosynthetic models of biosynthetic pathways. While these principles have been largely deciphered, software that leverages these rules to automatically generate visualisations of biosynthetic models has not yet been developed. To enable high-quality automated visualisations of natural product biosynthetic pathways, we developed RAIChU (Reaction Analysis through Illustrating Chemical Units), which produces depictions of biosynthetic transformations of PKS, NRPS, and hybrid PKS/NRPS systems from predicted or experimentally verified module architectures and domain substrate specificities. RAIChU also boasts a library of functions to perform and visualise reactions and pathways whose specifics (e.g., regioselectivity, stereoselectivity) are still difficult to predict, including terpenes, ribosomally synthesised and posttranslationally modified peptides and alkaloids. Additionally, RAIChU includes 34 prevalent tailoring reactions to enable the visualisation of biosynthetic pathways of fully maturated natural products. RAIChU can be integrated into Python pipelines, allowing users to upload and edit results from antiSMASH, a widely used BGC detection and annotation tool, or to build biosynthetic PKS/NRPS systems from scratch. RAIChU's cluster drawing correctness (100%) and drawing readability (97.66%) were validated on 5000 randomly generated PKS/NRPS systems, and on the MIBiG database. The automated visualisation of these pathways accelerates the generation of biosynthetic models, facilitates the analysis of large (meta-) genomic datasets and reduces human error. RAIChU is available at https://github.com/BTheDragonMaster/RAIChU and https://pypi.org/project/raichu. Scientific contribution RAIChU is the first software package capable of automating high-quality visualisations of natural product biosynthetic pathways. By leveraging universal biosynthetic rules, RAIChU enables the depiction of complex biosynthetic transformations for PKS, NRPS, ribosomally synthesised and posttranslationally modified peptide (RiPP), terpene and alkaloid systems, enhancing predictive and analytical capabilities. This innovation not only streamlines the creation of biosynthetic models, making the analysis of large genomic datasets more efficient and accurate, but also bridges a crucial gap in predicting and visualising the complexities of natural product biosynthesis. [ABSTRACT FROM AUTHOR]

The liquid-liquid phase separation of biopolymers in living cells contains multiple interactions and occurs in a dynamic environment. Resolving the regulation mechanism is still a challenge. In this work, we designed a series of peptides (XXLY)6SSSGSS and studied their complexation and coacervation behavior with single-stranded oligonucleotides. The "X" and "Y" are varied to combine known amounts of charged and non-charged amino acids, together with the introduction of secondary structures and pH responsiveness. Results show that the electrostatic interaction, which is described as charge density, controls both the strength of complexation and the degree of chain relaxation, and thus determines the growth and size of the coacervates. The hydrophobic interaction is prominent when the charges are neutralized. Interestingly, the secondary structures of peptides exhibit profound effect on the morphology of the phases, such as solid phase to liquid phase transition. Our study gains insight into the phase separation under physiological conditions. It is also helpful to create coacervates with desirable structures and functions. [ABSTRACT FROM AUTHOR]

Tirzepatide is the first ever once-weekly, injectable gastric inhibitory peptide/glucagon-like peptide 1 (GIP/GLP-1) dual agonist approved by the European Medicines Agency for type 2 diabetes. The efficacy and safety of tirzepatide have been evaluated in five global, randomized, double-blind or open-label, phase 3 studies which enrolled over 7000 people living with type 2 diabetes, across various stages of disease and with different characteristics at baseline. In this short commentary we report the salient data of the most recent trials on tirzepatide and GLP-1 receptor agonists from a clinical point of view, with the aim of highlighting similarities and mutual differences. [ABSTRACT FROM AUTHOR]

Development of potent and broad-spectrum antimicrobial peptides (AMPs) could help overcome the antimicrobial resistance crisis. We develop a peptide language-based deep generative framework (deepAMP) for identifying potent, broad-spectrum AMPs. Using deepAMP to reduce antimicrobial resistance and enhance the membrane-disrupting abilities of AMPs, we identify, synthesize, and experimentally test 18 T1-AMP (Tier 1) and 11 T2-AMP (Tier 2) candidates in a two-round design and by employing cross-optimization-validation. More than 90% of the designed AMPs show a better inhibition than penetratin in both Gram-positive (i.e., S. aureus) and Gram-negative bacteria (i.e., K. pneumoniae and P. aeruginosa). T2-9 shows the strongest antibacterial activity, comparable to FDA-approved antibiotics. We show that three AMPs (T1-2, T1-5 and T2-10) significantly reduce resistance to S. aureus compared to ciprofloxacin and are effective against skin wound infection in a female wound mouse model infected with P. aeruginosa. In summary, deepAMP expedites discovery of effective, broad-spectrum AMPs against drug-resistant bacteria. New approaches to develop antimicrobial agents are urgently needed. In this study, the authors develop a peptide language-based deep generative model to design broad-spectrum antimicrobial peptides against drug-resistant bacteria and validate promising candidates in a wound mouse model. [ABSTRACT FROM AUTHOR]