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A selected ion monitoring (SIM) approach combined with high resolution mass spectrometry is employed to identify and distinguish common SARS-CoV2 omicron and recombinant variants in clinical specimens. Mutations within the receptor binding domain (RBD) within the surface spike protein of the virus result in a combination of peptide segments of unique sequence and mass that were monitored to detect BA.2.75 (including CH.1.1) and XBB (including 1.5) variants prevalent in the state's population in early 2023. SIM detection of pairs of peptides unique to each variant were confidently detected and differentiated in 57.3% of the specimens, with a further 10 or 17.5% (for a total of 74.8%) detected based on a single peptide biomarker. The BA.2.75 sub-variant was detected in 18.7%, while recombinant variants XBB and XBB.1.5 were detected in 13.3% and 25.3% of the specimens respectively, consistent with circulating levels in the population characterised by RT-PCR. Virus was detected in 75 SARS-CoV2 positive specimens by mass spectrometry down to the low or mid 104 copy level, with a single false positive and no false negative identified. This article is the first paper to characterise recombinant strains of the SARS-CoV2 virus by this, or any other, MS method. [ABSTRACT FROM AUTHOR]

Angiotensin and kinin metabolic pathways are reported to be altered by many diseases, including COVID-19. Monitoring levels of these peptide metabolites is important for understanding mechanisms of disease processes. In this paper, we report dimethyl labeling of amines in peptides by addition of formal-dehyde to samples and deutero-formaldehyde to internal standards to generate nearly identical isotopic standards with 4 m/z units larger per amine group than the corresponding analyte. We apply this approach to rapid, multiplexed, absolute LC-MS/MS quantitation of renin angiotensin system (RAS) and kallikrein-kinin system (KKS) peptides in human blood serum. Limits of detection (LODs) were obtained in the low pg mL−1 range with 3 orders of magnitude dynamic ranges, appropriate for determinations of normal and elevated levels of the target peptides in blood serum and plasma. Accuracy is within ±15% at concentrations above the limit of quantitation, as validated by spike-recovery in serum samples. Applicability was demonstrated by measuring RAS and KKS peptides in serum from COVID-19 patients, but is extendable to any class of peptides or other small molecules bearing reactive –NH2 groups. [ABSTRACT FROM AUTHOR]

Sequential peptide coupling plays a central role in chemical protein synthesis. This paper describes a new peptide derivative, peptide-aminothiazoline (At), whereof the C-terminus is functionalized with 2-aminothiazoline. Peptide-At streamlined the sequential peptide ligation in a one-pot manner and demonstrated the convergent synthesis of a circular protein and homogeneous glycoproteins. [ABSTRACT FROM AUTHOR]

By establishing both a highly efficient phosphonamidate formation and a RuCp-catalyzed cleavage of an allyl linker, the solid-phase synthesis of Fmoc-(GlyP(OBn))6-OH/DIEA, a protected form of a new type of unnatural peptide α-amino phosphonic acid oligomer (APO), has been realized. [ABSTRACT FROM AUTHOR]

This paper presents compression molding of peptide assemblies with low-density polyethylene (LDPE) for the robust production of antimicrobial polymeric films. These films show a significant reduction of colony-forming units and plaque-forming units. Moreover, they significantly inhibited the growth of three different fungi. These innovative active polymeric films can potentially be applied for medical device wrapping, food packaging, and agriculture applications. [ABSTRACT FROM AUTHOR]

This paper is the first report of a non-competitive fluorescence polarization immunoassay (NC-FPIA) using a peptide as a tracer. The NC-FPIA can easily and quickly quantify the target after simply mixing them together. This feature is desirable for point-of-need applications such as clinical diagnostics, infectious disease screening, on-site analysis for food safety, etc. In this study, the NC-FPIA was applied to detect CD9, which is one of the exosome markers. We succeeded in detecting not only CD9 but also CD9 expressing exosomes derived from HeLa cells. This method can be applied to various targets if a tracer for the target can be prepared, and expectations are high for its future uses. [ABSTRACT FROM AUTHOR]

Photorelease complexes represent a class of agents for which UV-visible light triggers the expulsion of a specfic molecule that is intrinsically part of the inner coordination sphere or held in close proximity to the metal centre. The reaction does not occur in the ground-state complex and requires a photon, but an additional agent may be present that facilitates the release process. In this context, the perspective article covers recent papers from the past five years (2017–2021) on metal-based complexes containing ligands that are expelled under light activation. In addition, the examples primarily focus on ligands with potential biological activity and have specfic therapeutic applications. Some examples include NO, CO, Cl−, peptides, pharmacophores and redox-active compounds. [ABSTRACT FROM AUTHOR]

This is the tenth Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from December 2016. This ASU review deals with all aspects of the analytical atomic spectrometry speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. The review does not cover fractionation, which is sometimes termed operationally defined speciation. As with all ASU reviews the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to, or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. For this reason molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. As in previous years, As speciation continues to dominate the current literature with a significant number of publications concerning Hg and Se speciation and ‘biomolecules’, in which category a number of papers covered in the Se section could also belong. The number of elements covered in these updates also continues to rise with speciation analysis of over 20 elements reported this year. [ABSTRACT FROM AUTHOR]

The fabrication of functional molecular devices constitutes one of the most important current challenges for chemical sciences. The complex processes accomplished by living systems continuously demand the assistance of non-covalent interactions between molecular building blocks. Additionally, these building blocks (proteins, membranes, nucleotides) are also constituted by self-assembled structures. Therefore, supramolecular chemistry is the discipline required to understand the properties of the minimal self-assembled building blocks of living systems and to develop new functional smart materials. In the first part of this feature article, we highlight selected examples of the preparation of supramolecular membrane transporters with special emphasis on the application of dynamic covalent bonds. In the second section of the paper we review recent breakthroughs in the preparation of peptide nanotube hybrids with functional applications. The development of these devices constitutes an exciting process from where we can learn how to understand and manipulate supramolecular functional assemblies. [ABSTRACT FROM AUTHOR]

Milk is a natural suspension of essential nutrients and can be exploited not only as a beverage consumed directly or transformed into a range of traditional dairy foods, but also as a source of ingredients for food product innovation. In addition, by-products from the dairy industry, which used to constitute an economical and environmental problem, are still rich in proteins, lactose and minerals. Therefore, from a green point of view, they can be valorized and are being exploited for multiple food and non-food applications. This paper aims to give an overview of the different applications of milk ingredients and by-products from the dairy industry. Additionally, enzymatic modification and production of bioactive peptides and bioemulsifiers broaden their functionality and applicability. Finally, a critical review of the most promising aspects as well as some features that need further development is presented. The unmet needs, the cross fertilization in between protein domains, the carbon footprint requirements, the environmental necessities, the health and wellness new demands, etc. are dominant factors in the search for an innovation approach outlining the potential that these “apparent” constraints oblige science and technology to account for. The adjacent technology analysis opportunity that such a review generates is, in essence, an open innovation step. [ABSTRACT FROM AUTHOR]

Peptides from scorpion venom represent one of the most promising drug sources for drug discovery for some specific diseases. Current challenges in their separation include high complexity, high homologies and the huge range of peptides. In this paper, a modified strong cation exchange material, named MEX, was utilised for the two-dimensional separation of peptides from complex scorpion venom. The silica-based MEX column was bonded with two functional groups; benzenesulfonic acid and cyanopropyl. To better understand its separation mechanisms, seven standard peptides with different properties were employed in an evaluation study, the results of which showed that two interactions were involved in the MEX column: electrostatic interactions based on benzenesulfonic acid groups dominated the separation of peptides; weak hydrophobic interactions introduced by cyanopropyl groups increased the column's selectivity for peptides with the same charge. This characteristic allowed the MEX column to overcome some of the drawbacks of traditional strong cation exchange (SCX) columns. Furthermore, the study showed the great effects of the acetonitrile (ACN) content, the sodium perchlorate (NaClO4) concentration and the buffer pH in the mobile phase on the peptides’ retention and separation selectivity on the MEX column. Subsequently, the MEX column was combined with a C18 column to establish an off-line 2D-MEX × C18 system to separate peptides from scorpion Buthus martensi Karsch (BmK) venom. Due to complementary separation mechanisms in each dimension, a high orthogonality of 47.62% was achieved. Moreover, a good loading capacity, excellent stability and repeatability were exhibited by the MEX column, which are beneficial for its use in future preparation experiments. Therefore, the MEX column could be an alternative to the traditional SCX columns for the separation of peptides from scorpion venom. [ABSTRACT FROM AUTHOR]

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as coprisamide A from a bacterium isolated from Copris tripartitus. [ABSTRACT FROM AUTHOR]

Several limitations of 18F and other non-metallic isotopes have been emphasized by the development of macromolecular biotargeting agents for cancer, including peptides, antibodies, fragments and oligonucleotides, which typically have biological half-lives that are much longer than the radioactive half-life of 18F. Based on the 18F-FDG success story, we can wonder whether all critical criteria are or can be fulfilled for the radiometallated bioconjugates to start out from the crowd and which metals have the best chance of success. In this paper we give a brief overview of radiometal isotopes having the potential for PET imaging in terms of physical properties, production capacity and associated chemistry. [ABSTRACT FROM AUTHOR]

This paper presents a selective differential sensing method based on diffusion modulation of the target molecules through suspended Tobacco mosaic virus-like particles modified with binding peptides for TNT sensing in solution. [ABSTRACT FROM AUTHOR]

The key roles played by phospholipids in many cellular processes, has led to the development of model systems, to explore both lipid–lipid and lipid–peptide interactions. Biomimetic giant unilamellar vesicles represent close facsimiles of in vivo cellular membranes, although currently their widespread use in research is hindered by difficulties involving their integration into high-throughput techniques, for exploring membrane biology intensively in situ. This paper presents an integrated microfluidic device for the production, manipulation and high-throughput analysis of giant unilamellar vesicles. Its utility is demonstrated by exploring the lipid interaction dynamics of the pore-forming antimicrobial peptide melittin, assessed through the release of fluorescent dyes from within biomimetic vesicles, with membrane compositions similar to mammalian plasma membranes. [ABSTRACT FROM AUTHOR]

In this paper the reactivity of K15H[Zr(α2-P2W17O61)2]·25H2O (1), a Zr(iv)-substituted Wells–Dawson polyoxometalate, is examined towards a series of Gly–Aa, Aa–Gly or Aa–Ser dipeptides, in which the nature and the size of the Aa amino acid side chain were varied. The rate of peptide bond hydrolysis, determined by 1H NMR experiments, in Gly–Aa dipeptides is strongly dependent on the molecular volume and the chemical structure of the Aa side chain. When the volume of the aliphatic side chain of the Aa residue in Gly–Aa increased, a clear decrease in the hydrolysis rate was observed. Replacing one α-H in the C-terminal Gly residue of Gly–Gly by a methyl group (Gly–Ala) resulted in a 6-fold reactivity decrease, pointing towards the importance of steric factors for efficient peptide bond hydrolysis. The rate constants for peptide bond hydrolysis in Gly–Aa dipeptides at pD 5.0 and 60 °C ranged from 208.0 ± 15.6 × 10−6 min−1 for Gly–Ser to 5.0 ± 1.0 × 10−6 min−1 for Gly–Glu, reflecting the influence of the different nature of the amino acid side chains on the hydrolysis rate. Faster hydrolysis was observed for peptides containing Ser and Thr since the hydroxyl group in their side chain is able to facilitate amide bond hydrolysis by promoting an N→O acyl rearrangement. Peptides containing positively charged side chains at pD 5.0 show enhanced hydrolysis rates as a result of the secondary electrostatic interactions with the negatively charged surface of the polyoxometalate, which stabilize the peptide–polyoxometalate complex. A slow hydrolysis rate was observed for Gly–Glu, because of the preferential coordination of the carboxylate group in the side chain of Glu to Zr(iv), which prevents coordination of the peptide carbonyl group and its activation towards hydrolysis. [ABSTRACT FROM AUTHOR]

All stakeholders in cultural heritage share an interest in fabrication methods and material technology. Until now methods for analysis of organic materials, particularly proteins, have not been widely available to researchers at cultural institutions. This paper will describe an analytical method for the identification of collagen-based materials from soft tissue sources and show examples of its application to diverse museum objects. The method, peptide mass fingerprinting (PMF), uses enzymatic digestion of extracted proteins to produce a mixture of peptides. The mass spectrum of the mixture contains characteristic marker ions―a peptide mass fingerprint―which are compared to species-specific markers from references as the basis of identification. Preliminary results indicate that analysis of materials from aged samples, several different tissue types, and tanned or untanned materials yields comparable PMF results. Significantly, PMF is simple, rapid, sensitive and specific, has been implemented in a museum laboratory, and is being practiced successfully by non-specialists. [ABSTRACT FROM AUTHOR]

We have recently reported the synthesis of enantiomerically pure CF3-oxazolidine pseudoprolines (CF3-ΨPro). Complete NMR studies, together with DFT calculations, have highlighted the marked stereoelectronic effects of the CF3 group on these new proline surrogates. In this paper, we describe for the first time the conformational features of dipeptides incorporating one CF3-ΨPro residue. Extensive NMR analyses have been carried out in solution and revealed the presence of a stable type-VI β-turn in a pseudotetrapeptide sequence. [ABSTRACT FROM AUTHOR]

Phytochelatins (PCs) consist of alternating glutamic acid and cysteine residues ([γGlu–Cys]–Xaa) and are responsible for binding to heavy metals for cellular metal homeostasis and detoxification. This paper describes the papain-catalyzed synthesis of cysteine-rich peptides as potential PC mimics. By adjusting the feed ratio of l-cysteine ethyl ester (l-Et-Cys) and l-glutamic acid diethyl ester (l-(Et)2-Glu) followed by de-esterification, α-linked oligo(l-Glu-co-47%l-Cys) was prepared that closely matches the 1 : 1 l-Glu-to-l-Cys molar ratio of PC peptides. Plots of absorbance difference as a function of total metal-to-peptide ([M]total–[P]total) molar ratio were constructed for titrations with Zn(ii), Cd(ii), Co(ii) and Ni(ii). A series of equations were generated to evaluate dissociation constants and the number of metal ions per peptide molecule in metal–peptide complexes. All of the four complexes have on average two oligo(l-Glu-co-47%l-Cys) molecules per divalent cation. The binding of metals to oligo(l-Glu-co-47%l-Cys) weakens in the order of Cd(ii) ＞ Zn(ii) ＞ Ni(ii) ＞ Co(ii), the same trend observed for [(γGlu–Cys)4]–Gly. The peptide quantity required to sequester a given amount of Zn(ii) and Cd(ii) when using oligo(l-Glu-co-47%l-Cys) is only about twice as much as the quantity for perfect sequence peptide (γGlu–Cys)2–Gly. Furthermore, when [M]total is low, random oligo(l-Glu-co-47%l-Cys) sequesters much higher fractions of Co(ii) and Ni(ii) than does (γGlu–Cys)2–Gly. Results from this work provide the first evidence that, in some cases, uniform peptides synthesized by tedious solid or liquid phase peptide synthetic methods, can be replaced with peptide mixtures prepared by facile protease-catalyzed peptide synthetic methods without substantial loss in product performance. [ABSTRACT FROM AUTHOR]

Several methods can be used to improve the enrichment of phosphorylated proteins. In this paper, phosphopeptides were enriched using magnetic iron(ii,iii) oxide (magnetite, Fe3O4) nanoparticles (NPs) on a radiate microstructure silicon chip and then analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) without further purification processes. We have developed a radiate microstructure chip on which samples can be concentrated for analysis by MALDI-TOFMS. The phosphoprotein digests and magnetic iron oxide NPs aqueous solution were deposited onto the central zone of the radiate microstructure silicon chip and enabled the on-chip enrichment of phosphopeptides. Microscopic analysis confirmed that the applied samples were confined to the central zone. Sample spots focused on the chip were much smaller than those on an unmodified plate with the same total volume. Different additives were used and optimized processes were performed to minimize non-phosphopeptides interference. These data collectively demonstrate that our on-chip phosphopeptide enrichment protocol is a rapid and easy-to-use method for phosphoproteome analysis. [ABSTRACT FROM AUTHOR]

The paper reports on a novel localized surface plasmon resonance (LSPR) substrate architecture for the immobilization and detection of histidine-tagged peptides. The LSPR interface consists of an ITO (indium tin oxide) substrate coated with gold nanostructures. The latter are obtained by thermal deposition of a thin (2 nm thick) gold film followed by post-annealing at 500 °C. The LSPR interface was coated with poly[3-(pyrrolyl)carboxylic acid] thin films using electrochemical means. The ability of the LSPR interfaces coated with poly[3-(pyrrolyl)carboxylic acid] to chelate copper ions was investigated. Once loaded with metal ions, the modified LSPR interface was able to bind specifically to histidine-tagged peptides. The binding process was followed using LSPR. [ABSTRACT FROM AUTHOR]

A novel aptamer biosensor for fast tetracyclines determination was established and illustrated in this paper. The tetracyclines aptamer as a specific affinity molecule was immobilized on the surface of the glassy carbon (GC) electrodes. It can specifically bind tetracyclines quickly in milk and other samples without sample treatment. Subsequently, the electrochemical signals are produced and measured accurately. The linear relationship between the currents and the tetracyclines concentration is 0.1–100ng ml−1. The sensitivity limit of the device is 1ng ml−1. The detection time is 5 min. [ABSTRACT FROM AUTHOR]

Advances in mass spectrometry and capillary-format separation continue to improve the sensitivity of protein analysis. Of equal importance is the miniaturization of sample pretreatment such as enrichment and proteolysis. In a previous report (Nesbitt et al., Electrophoresis, 2008, 29, 466–474), nanoliter-volume protein enrichment, tryptic digestion, and partial separation was demonstrated in capillary electrophoresis followed by MALDI mass spectral analysis. A discontinuous buffer system, consisting of ammonium (pH 10) and acetate (pH 4), was used to create a pH junction inside the capillary, trapping a protein with a neutral isoelectric point, myoglobin (pI7.2). Moreover, co-enrichment of myoglobin with trypsin led to an in-capillary digestion. In this paper, the ability of this discontinuous buffer system to perform similar in-capillary sample pretreatment on proteins with moderately acidic and basic pIwas studied and reported. Lentil lectin (pI8.6) and a multi-phosphorylated protein, β-casein (pI5.1), were selected as model proteins. In addition to the previously shown tryptic digestion, proteolysis with endoproteinase Asp-N was also performed. Digestion of these acidic and basic pIproteins produced a few peptides with extreme pIvalues lying outside the trapping range of the discontinuous buffer. An alteration in the peptide trapping procedure was made to accommodate these analytes. Offline MALDI mass spectral analysis confirmed the presence of the expected peptides. The presented miniaturized sample pretreatment methodology was proven to be applicable on proteins with a moderately wide range of pI.Flexibility in the choice of protease was also evident. [ABSTRACT FROM AUTHOR]

The detection of peptides with mass spectrometry from volume-limited biological samples is a challenging task due to low sample volume, a broad range of peptide concentrations down to trace levels, endogenous high proteins and salt levels. Previously, a microspotting method was presented for trace-level peptide detection with MALDI-MS from sub-microlitre samples with biological salt levels. However, in the presence of proteins, peptide signals are significantly reduced. This paper presents a novel dialysis device for removal of proteins from sub-microlitre samples using a semipermeable hollow fiber membrane to enhance peptide detection. A dialysis device was constructed to perform sub-microlitre dialysis to remove proteins from complex samples. Angiotensin I was used as a model peptide in the presence of 350 mg L−1 BSA prepared in physiological saline to mimic biological samples. In the absence of BSA, clear angiotensin I peaks were seen at 250 pM, yet in the presence of the BSA, 10 nM angiotensin I was barely detected. After dialysis, peak detection was improved to a 500 pM level. Protein removal and peptide recovery (approximately 66%) were determined using CE-LIF. Clinical vitreous samples as low as 200 nL were successfully dialyzed in 30 min and a 3-fold increase in peptide peaks were detected with greatly improved signals. This method is simple and can be a useful technique for trace level peptide detection from volume-limited biological samples. [ABSTRACT FROM AUTHOR]

A new strategy to fabricate an aptamer-protein nanowire at an electrode surface is reported in this paper, and a simple electrochemical method to determine the concentration of a protein is proposed with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

This paper describes a new fluorescent chemosensor for phosphorylated peptide, which comprises a rigid trans-4,4′-diazastilbene and two Zn(ii)-Dpa (2,2′-dipicolylamine) units; this chemosensor sequence-selectively binds to a (i, i+ 1) bis-phosphorylated peptide and displays a dual-emission fluorescence change. [ABSTRACT FROM AUTHOR]