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Exhaled breath condensate (EBC) is used as a promising noninvasive diagnostic tool in the field of respiratory medicine. EBC is achieved by cooling exhaled air, which contains aerosolized particles and volatile compounds present in the breath. This method provides useful information on the biochemical and inflammatory state of the airways. In respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis, EBC analysis can reveal elevated levels of biomarkers such as hydrogen peroxide, nitric oxide and various cytokines, which correlate with oxidative stress and inflammation. 
Furthermore, the presence of certain volatile organic compounds (VOCs) in EBC has been linked to specific respiratory conditions, potentially serving as disease-specific fingerprints. The noninvasive nature of EBC sampling makes it particularly useful for repeated measures and for use in vulnerable populations, including children and the elderly. Despite its potential, the standardization of collection methods, analytical techniques and interpretation of results currently limits its use in clinical practice. 
Nonetheless, EBC holds significant promise for improving the diagnosis, monitoring and therapy of respiratory diseases.
In this tutorial we will present the latest advances in EBC research in airway diseases and future prospects for clinical applications of EBC analysis, including the application of the Omic sciences for its analysis.&#xD., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Alkyl radicals generated via an acridine photocatalyzed decarboxylation reaction of feedstock carboxylic acids engage with a range of cyclic imine-BF 3 complexes to provide α-functionalized azacycles in an operationally simple process. A three-component variant of this transformation incorporating [1.1.1]propellane as an additional reaction partner enables the synthesis of valuable bicyclopentane (BCP)-containing azacycles. Reactions exhibit good functional group compatibility, enabling late-stage modification of complex bioactive molecules.

Antimicrobial peptides (AMPs) are a promising alternative to antibiotics in the fight against multi-drug resistant and immune system-evading bacterial infections. Protegrins are porcine cathelicidins which have been identified in porcine leukocytes. Protegrin-1 is the best characterized family member and has broad antibacterial activity by interacting and permeabilizing bacterial membranes. Many host defense peptides (HDPs) like LL-37 or chicken cathelicidin 2 (CATH-2) have also been shown to have protective biological functions during infections. In this regard, it is interesting to study if Protegrin-1 has the immune modulating potential to suppress unnecessary immune activation by neutralizing endotoxins or by influencing the macrophage functionality in addition to its direct antimicrobial properties. This study showed that Protegrin-1 neutralized lipopolysaccharide- (LPS) and bacteria-induced activation of RAW macrophages by binding and preventing LPS from cell surface attachment. Furthermore, the peptide treatment not only inhibited bacterial phagocytosis by murine and porcine macrophages but also interfered with cell surface and intracellular bacterial survival. Lastly, Protegrin-1 pre-treatment was shown to inhibit the amastigote survival in Leishmania infected macrophages. These experiments describe an extended potential of Protegrin-1's protective role during microbial infections and add to the research towards clinical application of cationic AMPs., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This study investigates the hydrogen-bond geometry in six two-component solid systems composed of quinoline and chloro-nitrobenzoic acids. New X-ray diffraction studies were conducted using both the conventional independent-atom model and the more recent Hirshfeld atom-refinement method, with the latter providing precise hydrogen-atom positions. The systems can be divided into salts (the hydrogen atom transferred to the quinoline nitrogen), cocrystals (the hydrogen atom retained by the acid), and intermediate structures. Solid-state NMR experiments corroborated the X-ray diffraction-derived H-N distances. DFT calculations, using five functionals including hybrid B3LYP and PBE0, showed varying energy profiles for the hydrogen bonds, with notable differences across functionals. These calculations revealed different preferences for salt or cocrystal structures, depending on the functional used. Path-integral molecular dynamics simulations incorporating nuclear quantum effects demonstrated significant hydrogen-atom delocalization, forming a hydrogen-bond continuum, and provided average N-H distances in excellent agreement with experimental results. This comprehensive experimental and theoretical approach highlights the complexity of multicomponent solids. The study emphasizes that the classification into salts or cocrystals is frequently inadequate, as the hydrogen atom is often significantly delocalized in the hydrogen bond. This insight is crucial for understanding and predicting the behavior of such systems in pharmaceutical applications., (© 2024 Wiley‐VCH GmbH.)

The ability to adapt to osmotically diverse and fluctuating environments is critical to the survival and resilience of bacteria that colonize the human gut and urinary tract. Environmental stress often provides cross-protection against other challenges and increases antibiotic tolerance of bacteria. Thus, it is critical to understand how E. coli and other microbes survive and adapt to stress conditions. The osmotically inducible protein Y (OsmY) is significantly upregulated in response to hypertonicity. Yet its function remains unknown for decades. We determined the solution structure and dynamics of OsmY by nuclear magnetic resonance spectroscopy, which revealed that the two Bacterial OsmY and Nodulation (BON) domains of the protein are flexibly linked under low- and high-salinity conditions. In-cell solid-state NMR further indicates that there are no gross structural changes in OsmY as a function of osmotic stress. Using cryo-electron and super-resolution fluorescence microscopy, we show that OsmY attenuates plasmolysis-induced structural changes in E. coli and improves the time to growth resumption after osmotic upshift. Structure-guided mutational and functional studies demonstrate that exposed hydrophobic residues in the BON1 domain are critical for the function of OsmY. We find no evidence for membrane interaction of the BON domains of OsmY, contrary to current assumptions. Instead, at high ionic strength, we observe an interaction with the water channel, AqpZ. Thus, OsmY does not play a simple structural role in E. coli but may influence a cascade of osmoregulatory functions of the cell., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Cross-linking, also called tanning, improves mechanical properties of leather and also increases its enzymatic and thermal stability. As a final product, leather has an ultimate tensile strength (σ) of 8-25 MPa and an elongation at break (ε) of >30 %. Mycelium-based materials are a sustainable alternative to leather. Here, the effect of cross-linkers was assessed on mechanical properties of Schizophyllum commune mycelium sheets . To this end, glutaraldehyde and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) were used as well as extracts of Ligustrum vulgare leaves , and bark of Acacia mearnsii and Caesalpinia spinosa. Untanned sheets had a σ of 7.8 MPa and an ε of 15.2 %, while the best overall combination of strength and elasticity was obtained with 0.1 % glutaraldehyde with a σ of 11.1 MPa and an ε of 14.6 %. Cross-linking also increased enzymatic stability and reduced mycelial water absorption but did not result in increased thermal stability. Fourier transform infrared spectroscopy (FTIR), 1D nuclear magnetic resonance spectroscopy (NMR), and amino acid analysis showed that glutaraldehyde bound both protein amino groups and polysaccharide hydroxyl groups by forming Schiff bases and acetals, respectively. Together, synthetic and vegetable cross-linkers can be used to obtain mycelium materials with leather-like tensile strength., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

The study of fluid absorption, particularly that of water, into nanoporous materials has garnered increasing attention in the last decades across a broad range of disciplines. However, most investigation approaches to probe such behaviors are limited by characterization conditions and may lead to misinterpretations. In this study, a combined MRI and MAS NMR method was used to study a nanoporous silica glass to acquire information about its structural framework and interactions with confined water in a native humid environment. Specifically, MRI was used for a quantitative analysis of water extent. While MAS NMR techniques provided structural information of silicate materials, including interactive surface area and framework packing. Analysis of water spin-spin relaxation times (T 2 ) suggested differences in water confinement within the characterized framework. Subsequent unsuccessful delivery of paramagnetic molecule into the pores enabled a quantitative assessment of the dimensions that "bottleneck" the pores. Finally, pore sizes were derived from the paramagnetic molecular size, density function theory (DFT) simulation and characterizations on standard samples. Our result matches with Brunauer-Emmett-Teller (BET) analysis that the pore size is less than 1.3 nm. The use of a paramagnetic probe for pore size determination introduces a new approach of characterization in the liquid phase, offering an alternative to the conventional BET analysis that uses gas molecule as probes., (© 2024 Wiley-VCH GmbH.)

The chemical structure of piperidine has a unique ability to combine with other molecular fragments. This fact makes it possible to actively use it as an effective basis for the creation of new drug-like substances. Thus, the aim of the current investigation was to study the acute toxicity, local anesthetic potency, and antiarrhythmic activity of the two new synthesized piperidine derivatives under laboratory codes LAS-286 and LAS-294 (local anesthetic substances). The Bulbring & Wajda animal model and method of determining the nociception threshold during electrical stimulation was used to investigate the action of the substance during infiltration anesthesia. An antiarrhythmic activity was observed by the aconitine-induced rat arrhythmia model. Additionally, these compounds were studied in relation to molecular docking to delineate the structure-activity relationships. The tested piperidine derivatives had a low toxicity in the subcutaneous and intravenous administration routes. The experimental results showed a higher prolonged and pronounced local anesthetic activity for LAS-286 at a 0.5% concentration, compared to the reference preparations. The low dosage of 0.1 mg/kg of LAS-294 demonstrated a pronounced preventive antiarrhythmic effect in 90% of cases on the development of mixed arrhythmia, caused by aconitine. The results of molecular docking confirmed a higher binding affinity of the tested piperidines with the Nav1.4 and Nav1.5 macromolecules. The results of the present study are very promising, because these piperidines have shown a high biological activity, which can suggest a potential therapeutic application in the future.

Inherently chiral compounds, such as calixarenes, are chiral due to a nonplanar three-dimensional (3D) structure. Determining their conformation is essential to understand their properties, with nuclear magnetic resonance (NMR) spectroscopy being one applicable method. Using alignment media to measure residual dipolar couplings (RDCs) to obtain structural information is advantageous when classical NMR parameters like the nuclear Overhauser effect (NOE) or J -couplings fail. Besides providing more accurate structural information, the alignment media can induce different orientations of enantiomers. In this study, we examined the ability of polyglutamates with different side-chain moieties─poly-γ-benzyl-l-glutamate (PBLG) and poly-γ- p -biphenylmethyl-l-glutamate (PBPMLG) ─to enantiodifferentiate the inherently chiral phenoxathiin-based thiacalix[4]arenes. Both media, in combination with two solvents, allowed for enantiodiscrimination, which was, to the best of our knowledge, proved for the first time on inherently chiral compounds. Moreover, using the experimental RDCs, we investigated the calix[4]arenes conformational preferences in solution, quantitatively analyzed the differences in the alignment of the enantiomers, and discussed the pitfalls of the use of the RDC analysis.

Antimicrobial resistance is a leading cause of mortality, calling for the development of new antibiotics. The fungal antibiotic plectasin is a eukaryotic host defence peptide that blocks bacterial cell wall synthesis. Here, using a combination of solid-state nuclear magnetic resonance, atomic force microscopy and activity assays, we show that plectasin uses a calcium-sensitive supramolecular killing mechanism. Efficient and selective binding of the target lipid II, a cell wall precursor with an irreplaceable pyrophosphate, is achieved by the oligomerization of plectasin into dense supra-structures that only form on bacterial membranes that comprise lipid II. Oligomerization and target binding of plectasin are interdependent and are enhanced by the coordination of calcium ions to plectasin's prominent anionic patch, causing allosteric changes that markedly improve the activity of the antibiotic. Structural knowledge of how host defence peptides impair cell wall synthesis will likely enable the development of superior drug candidates., (© 2024. The Author(s).)

A computational study was performed to unravel mechanisms underlying capillary electrophoresis enantioseparations of daclatasvir and its (R,R,R,R)-enantiomer with native and methylated β-cyclodextrins (β-CDs) as chiral selectors. Considering the enantioseparation results as benchmark, the structures of β-CD and seven methylated β-CDs were optimized by quantum mechanics, and their topography and computed molecular properties were compared. Furthermore, the electron charge density distribution of the macrocycles was also evaluated by calculating the molecular electrostatic potential of pivotal regions of native and methylated β-CDs. The function of hydrogen bonds in the complexation process of daclatasvir and the CDs was derived from quantum mechanics analysis and confirmed by molecular dynamics, as orthogonal computational techniques. The presence of a round-shaped cavity in the CDs used as chiral selector appeared as a necessary requirement for the enantioseparation of daclatasvir and its (R,R,R,R)-enantiomer. In this regard, it was confirmed that the round shape of the CDs is sustained by hydrogen bonds formed between adjacent glucopyranose units and blocking rotation of the linking glycosidic bonds. The presence of hydroxy groups at the 6-position of the glucopyranose units and the concurrent absence of hydroxy groups at the 2-position were evidenced as important factors for enantioseparation of daclatasvir and its enantiomer by methylated β-CDs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Diabetes mellitus is a severe endocrine disease that affects more and more people every year. Modern medical chemistry sets itself the task of finding effective and safe drugs against diabetes. This review provides an overview of potential antidiabetic drugs based on three heterocyclic compounds, namely morpholine, piperazine, and piperidine. Studies have shown that compounds containing their moieties can be quite effective in vitro and in vivo for the treatment of diabetes and its consequences.

Chlorosomes, the photosynthetic antenna complexes of green sulfur bacteria, are paradigms for light-harvesting elements in artificial designs, owing to their efficient energy transfer without protein participation. We combined magic angle spinning (MAS) NMR, optical spectroscopy and cryogenic electron microscopy (cryo-EM) to characterize the structure of chlorosomes from a bchQ mutant of Chlorobaculum tepidum . The chlorosomes of this mutant have a more uniform composition of bacteriochlorophyll (BChl) with a predominant homolog, [8Ethyl, 12Ethyl] BChl c , compared to the wild type (WT). Nearly complete 13 C chemical shift assignments were obtained from well-resolved homonuclear 13 C- 13 C RFDR data. For proton assignments heteronuclear 13 C- 1 H (hCH) data sets were collected at 1.2 GHz spinning at 60 kHz. The CHHC experiments revealed intermolecular correlations between 13 2 /3 1 , 13 2 /3 2 , and 12 1 /3 1 , with distance constraints of less than 5 Å. These constraints indicate the syn - anti parallel stacking motif for the aggregates. Fourier transform cryo-EM data reveal an axial repeat of 1.49 nm for the helical tubular aggregates, perpendicular to the inter-tube separation of 2.1 nm. This axial repeat is different from WT and is in line with BChl syn - anti stacks running essentially parallel to the tube axis. Such a packing mode is in agreement with the signature of the Q y band in circular dichroism (CD). Combining the experimental data with computational insight suggests that the packing for the light-harvesting function is similar between WT and bchQ , while the chirality within the chlorosomes is modestly but detectably affected by the reduced compositional heterogeneity in bchQ .

The origin of nuclear magnetic shielding in diamagnetic molecules is discussed, pointing out various contributions to the shielding from electrons and the effects of intra- and intermolecular interactions. In NMR practice, chemical shifts are determined first as the measure of shielding in observed samples. The descriptions of shielding and chemical shifts are not fully consistent. Gas phase studies permit the withdrawal of intermolecular contributions from shielding and obtaining the magnetic shielding data in isolated molecules. The shielding determination in molecules is possible using at least three methods delivering the reference shielding standards for selected nuclei. The known shielding of one magnetic nucleus can be transferred to other nuclei if the appropriate nuclear magnetic moments are available with satisfactory accuracy. It is possible to determine the nuclear magnetic dipole moments using the most advanced ab initio shielding calculations jointly with the NMR frequencies measurements for small-sized isolated molecules. Helium-3 gas is postulated as all the molecules' primary and universal reference standard of shielding. It can be easily applied using common deuterium lock solvents as the secondary reference standards. The measurements of absolute shielding are available for everyone with the use of standard NMR spectrometers.

Sensitivity enhanced dynamic nuclear polarization solid-state NMR is emerging as a powerful technique for probing the structural properties of conformationally homogenous and heterogenous biomolecular species irrespective of size at atomic resolution within their native environments. Herein we detail advancements that have made acquiring such data, specifically within the confines of intact bacterial and eukaryotic cell a reality and further discuss the type of structural information that can presently be garnered by the technique's exploitation. Subsequently, we discuss bottlenecks that have thus far curbed cellular DNP-ssNMR's broader adoption namely due a lack of sensitivity and spectral resolution. We also explore possible solutions ranging from utilization of new pulse sequences, design of better performing polarizing agents, and application of additional biochemical/ cell biological methodologies., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Chromatinized DNA is targeted by proteins and small molecules to regulate chromatin function. For example, anthracycline cancer drugs evict nucleosomes in a mechanism that is still poorly understood. We here developed a flexible method for specific isotope labeling of nucleosomal DNA enabling NMR studies of such nucleosome interactions. We describe the synthesis of segmental one-strand 13 C-thymidine labeled 601-DNA, the assignment of the methyl signals, and demonstrate its use to observe site-specific binding to the nucleosome by aclarubicin, an anthracycline cancer drug that intercalates into the DNA minor grooves. Our results highlight intrinsic conformational heterogeneity in the 601 DNA sequence and show that aclarubicin binds an exposed AT-rich region near the DNA end. Overall, our data point to a model where the drug invades the nucleosome from the terminal ends inward, eventually resulting in histone eviction and nucleosome disruption., (© 2024 The Authors. ChemBioChem published by Wiley-VCH GmbH.)

A starting thiacalix[4]arene can be easily transformed into oxidized phenoxathiin-based macrocycles 9 and 9', representing an unusual structural motif in calixarene chemistry. The presence of electron-withdrawing groups (SO 2 , SO) and the considerable internal strain caused by the condensed heterocyclic moiety render these molecules susceptible to nucleophilic attack. The reaction with various organolithium reagents provides a number of different products resulting from the cleavage of either the calixarene skeleton or the phenoxathiin group or both ways simultaneously. This enables the preparation of thiacalixarene analogues with unusual structural features, including systems containing a biphenyl fragment as a part of the macrocyclic skeleton. The above-described transformations, unparalleled in classical calixarene chemistry, clearly demonstrate the synthetic potential of this thiacalixarene subgroup., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Peptide deformylase (PDF) is involved in bacterial protein maturation processes. Originating from the interest in a new antibiotic, tremendous effort was put into the refinement of PDF inhibitors (PDFIs) and their selectivity. We obtained a full NMR backbone assignment the emergent additional protein backbone resonances of ecPDF 1-147 in complex with 2-(5-bromo-1 H -indol-3-yl)- N -hydroxyacetamide ( 2 ), a potential new structural scaffold for more selective PDFIs. We also determined the complex crystal structures of E. coli PDF (ecPDF fl) and 2 . Our structure suggests an alternative ligand conformation within the protein, a possible starting point for further selectivity optimization. The orientation of the second ligand conformation in the crystal structure points toward a small region of the S1' pocket, which differs between bacterial PDFs and human PDF. Moreover, we analyzed the binding mode of 2 via NMR TITAN line shape analysis, revealing an induced fit mechanism.

Humins, (side-)products of the acid-catalysed dehydration of carbohydrates, will be produced in substantial quantities with the development of industrial biorefining processes. Most structural knowledge about such humins is based on synthetic model humins prepared at lab-scale from typical carbohydrate(-derived) compounds. Here, we report the first extensive characterisation study of an industrial humin. The soluble humin was generated from pilot plant-scale methanolic cyclodehydration of D-fructose to 5-methoxymethyl-2-furfural (MMF), as part of the Avantium YXY® process to produce FDCA. Purification of the industrial humin followed by fractionation allowed isolation of a water-insoluble, high molecular weight fraction (WIPIH) and a water-soluble, low-to-middle molecular weight soluble fraction (WES). Characterisation by elemental analysis, thermogravimetry, IR and NMR spectroscopy and size exclusion chromatography provided a detailed picture of the humin structure in both fractions. Aided by a comprehensive NMR spectral library of furanic model compounds, we identified the main furanic building blocks and inter-unit linkages and propose a structure for this industrial humin sample. The WIPIH and WES fractions were found to be composed of furanic rings interconnected by short aliphatic chains containing a wide range of functionalities including alcohols, ethers, carboxylic acids, esters, aldehydes and ketones. The low level of crosslinking and high functional group content of the industrial humin differ from the more extensively studied, (highly over-)condensed synthetic model humins, towards which they can be considered intermediates. The structural and compositional insights into the nature of an actual industrial humin open up a broad spectrum of valorisation opportunities., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The lack of new antibiotics and the rapidly rising number of pathogens resistant to antibiotics pose a serious problem to mankind. In bacteria, the cell membrane provides the first line of defence to antibiotics by preventing them from reaching their molecular target. To overcome this entrance barrier, it has been suggested [1] that small Gold-Nanoparticles (AuNP) could possibly function as drug delivery systems for antibiotic ligands. Using actinonin-based ligands, we provide here proof-of-principle of AuNP functionalisation, the capability to bind and inhibit the target protein of the ligand, and the possibility to selectively release the antimicrobial payload. To this end, we successfully synthesised AuNP coated with thio-functionalised actinonin and a derivative. Interactions between 15 N-enriched His-peptide deformylase 1-147 from E. coli (His-ecPDF 1-147) and compound-coated AuNP were investigated via 2D 1 H- 15 N-HSQC NMR spectra proving the direct binding to His-ecPDF 1-147. More importantly by adding dithiothreitol (DTT), we show that the derivative is successfully released from AuNPs while still bound to His-ecPDF 1-147. Our findings indicate that AuNP-conjugated ligands can address and bind intracellular target proteins. The system introduced here presents a new delivery platform for antibiotics and allows for the easy optimisation of ligand coated AuNPs., (© 2023 The Authors. ChemMedChem published by Wiley-VCH GmbH.)

Microtubules (MTs) are key components of the eukaryotic cytoskeleton and are essential for intracellular organization, organelle trafficking and mitosis. MT tasks depend on binding and interactions with MT-associated proteins (MAPs). MT-associated protein 7 (MAP7) has the unusual ability of both MT binding and activating kinesin-1-mediated cargo transport along MTs. Additionally, the protein is reported to stabilize MTs with its 112 amino-acid long MT-binding domain (MTBD). Here we investigate the structural basis of the interaction of MAP7 MTBD with the MT lattice. Using a combination of solid and solution-state nuclear magnetic resonance (NMR) spectroscopy with electron microscopy, fluorescence anisotropy and isothermal titration calorimetry, we shed light on the binding mode of MAP7 to MTs at an atomic level. Our results show that a combination of interactions between MAP7 and MT lattice extending beyond a single tubulin dimer and including tubulin C-terminal tails contribute to formation of the MAP7-MT complex., (© 2024. The Author(s).)

Antimicrobial peptides are a promising class of potential antibiotics that interact selectively with negatively charged lipid bilayers. This paper presents the structural characterization of the antimicrobial peptides myxinidin and WMR associated with bacterial membrane mimetic micelles and bicelles by NMR, CD spectroscopy, and molecular dynamics simulations. Both peptides adopt a different conformation in the lipidic environment than in aqueous solution. The location of the peptides in micelles and bicelles has been studied by paramagnetic relaxation enhancement experiments with paramagnetic tagged 5- and 16-doxyl stearic acid (5-/16-SASL). Molecular dynamics simulations of multiple copies of the peptides were used to obtain an atomic level of detail on membrane-peptide and peptide-peptide interactions. Our results highlight an essential role of the negatively charged membrane mimetic in the structural stability of both myxinidin and WMR. The peptides localize predominantly in the membrane's headgroup region and have a noticeable membrane thinning effect on the overall bilayer structure. Myxinidin and WMR show a different tendency to self-aggregate, which is also influenced by the membrane composition (DOPE/DOPG versus DOPE/DOPG/CL) and can be related to the previously observed difference in the ability of the peptides to disrupt different types of model membranes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Porous aluminosilicates are functional materials of paramount importance as Lewis acid catalysts in the synthetic industry, yet the participating aluminum species remain poorly studied. Herein, a series of model aluminosilicate networks containing [L-AlO 3 ] (L = THF, Et 3 N, pyridine, triethylphosphine oxide (TEPO)) and [AlO 4 ] - centers were prepared through nonhydrolytic sol-gel condensation reactions of the spherosilicate building block (Me 3 Sn) 8 Si 8 O 20 with L-AlX 3 (X = Cl, Me, Et) and [Me 4 N] [AlCl 4 ] compounds in THF or toluene. The substoichiometric dosage of the Al precursors ensured complete condensation and uniform incorporation, with the bulky spherosilicate forcing a separation between neighboring aluminum centers. The materials were characterized by 1 H, 13 C, 27 Al, 29 Si, and 31 P MAS NMR and FTIR spectroscopies, ICP-OES, gravimetry, and N 2 adsorption porosimetry. The resulting aluminum centers were resolved by 27 Al TQ/MAS NMR techniques and assigned based on their spectroscopic parameters obtained by peak fitting (δ iso , C Q , η) and their correspondence to the values calculated on model structures by DFT methods. A clear correlation between the decrease in the symmetry of the Al centers and the increase of the observed C Q was established with values spanning from 4.4 MHz for distorted [AlO 4 ] - to 15.1 MHz for [THF-AlO 3 ]. Products containing exclusively [TEPO-AlO 3 ] or [AlO 4 ] - centers could be obtained (single-site materials). For L = THF, Et 3 N, and pyridine, the [AlO 4 ] - centers were formed together with the expected [L-AlO 3 ] species, and a viable mechanism for the unexpected emergence of [AlO 4 ] - was proposed.

While plastics-to-plastics recycling via melting and re-extrusion is often the preferred option due to a relatively low CO 2 footprint, this technique requires a highly sorted waste stream and plastic properties can often not be maintained. Obtaining aromatics, such as benzene, toluene, and xylene (BTX), via catalytic pyrolysis of polyolefins, such as polypropylene and polyethylene, offers another attractive recycling technology. In this process, a discarded crude oil refinery catalyst (ECAT) was previously shown to lower the unwanted formation of deactivating coke species compared to a fresh crude oil refinery catalyst (FCC-cat), while yielding 20 wt% aromatics from polypropylene. In this work, we study the underlying reaction mechanism for this chemical recycling process over the fresh and used refinery catalyst as well as a model system, not containing any zeolite material, using a combination of microscopy and spectroscopy. More specifically, by using in situ fluorescence microscopy, in situ infrared spectroscopy, in situ ultraviolet-visible spectroscopy as well as ex situ solid-state nuclear magnetic resonance, we observe highly fluorescent methylated aromatic intermediates that differ for the three catalyst materials under study both in their fluorescence, IR, UV-vis, and NMR spectroscopy features. This detailed micro-spectroscopic comparison informs which potential reaction intermediates lead to increased coke formation. Our results suggests that a next generation of catalyst materials for this process would profit from a higher accessibility and a milder acidity compared to an FCC-cat and shows the great potential of using ECAT to reduce coking and obtain a BTX stream, which could be become the chemical building blocks for the manufacturing of e.g. , plastics and coating materials., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

A new strategy to access α-functionalized alicyclic amines via their corresponding imine-BF 3 complexes is reported. Isolable imine-BF 3 complexes, readily prepared via dehydrohalogenation of N-bromoamines in a base-promoted/18-crown-6 catalyzed process followed by addition of boron trifluoride etherate, undergo reactions with a wide range of organometallic nucleophiles to afford α-functionalized azacycles. Organozinc and organomagnesium nucleophiles add at ambient temperatures, obviating the need for cryogenic conditions. In situ preparation of imine-BF 3 complexes provides access to α-functionalized morpholines and piperazines directly from their parent amines in a single operation. α-Functionalized morpholines can be elaborated further, for instance by installing a second substituent in the α'-position., (© 2023 Wiley-VCH GmbH.)

High-resolution NMR spectroscopy enabled us to characterize allosteric transitions between various functional states of the dimeric Escherichia coli Lac repressor. In the absence of ligands, the dimer exists in a dynamic equilibrium between DNA-bound and inducer-bound conformations. Binding of either effector shifts this equilibrium toward either bound state. Analysis of the ternary complex between repressor, operator DNA, and inducer shows how adding the inducer results in allosteric changes that disrupt the interdomain contacts between the inducer binding and DNA binding domains and how this in turn leads to destabilization of the hinge helices and release of the Lac repressor from the operator. Based on our data, the allosteric mechanism of the induction process is in full agreement with the well-known Monod-Wyman-Changeux model., Competing Interests: Competing interests statement:The authors declare no competing interest.

Polymer properties can be altered via lithium ion doping, whereby adsorbed Li + binds with H 2 O within the polymer chain. However, direct spectroscopic evidence of the tightness of Li + /H 2 O binding in the solid state is limited, and the impact of Li + on polymer sidechain packing is rarely reported. Here, we investigate a polystyrene/H 2 O/LiCl system using solid-state NMR, from which we determined a dipolar coupling of 11.4 kHz between adsorbed Li + and H 2 O protons. This coupling corroborates a model whereby Li + interacts with the oxygen atom in H 2 O via charge affinity, which we believe is the main driving force of Li + binding. We demonstrated the impact of hydrated Li + on sidechain packing and dynamics in polystyrene using proton-detected solid-state NMR. Experimental data and density functional theory (DFT) simulations revealed that the addition of Li + and the increase in the hydration levels of Li + , coupled with aromatic ring binding, change the energy barrier of sidechain packing and dynamics and, consequently, changes the glass transition temperature of polystyrene.

The binding of Host Defense Peptides (HDPs) to the endotoxin of Gram-negative bacteria has important unsolved aspects. For most HDPs, it is unclear if binding is part of the antibacterial mechanism or whether LPS actually provides a protective layer against HDP killing. In addition, HDP binding to LPS can block the subsequent TLR4-mediated activation of the immune system. This dual activity is important, considering that HDPs are thought of as an alternative to conventional antibiotics, which do not provide this dual activity. In this study, we systematically determine, for the first time, the influence of the O-antigen and Lipid A composition on both the antibacterial and anti-endotoxin activity of four HDPs (CATH-2, PR-39, PMAP-23, and PMAP36). The presence of the O-antigen did not affect the antibacterial activity of any of the tested HDPs. Similarly, modification of the lipid A phosphate (MCR-1 phenotype) also did not affect the activity of the HDPs. Furthermore, assessment of inner and outer membrane damage revealed that CATH-2 and PMAP-36 are profoundly membrane-active and disrupt the inner and outer membrane of Escherichia coli simultaneously, suggesting that crossing the outer membrane is the rate-limiting step in the bactericidal activity of these HDPs but is independent of the presence of an O-antigen. In contrast to killing, larger differences were observed for the anti-endotoxin properties of HDPs. CATH-2 and PMAP-36 were much stronger at suppressing LPS-induced activation of macrophages compared to PR-39 and PMAP-23. In addition, the presence of only one phosphate group in the lipid A moiety reduced the immunomodulating activity of these HDPs. Overall, the data strongly suggest that LPS composition has little effect on bacterial killing but that Lipid A modification can affect the immunomodulatory role of HDPs. This dual activity should be considered when HDPs are considered for application purposes in the treatment of infectious diseases.

The synthesis, characterization, and preliminary activity of an unprecedented tethered alkylidyne tungsten complex for ring expansion alkyne metathesis polymerization (REAMP) are reported. The tethered alkylidyne 7 is generated rapidly by combining alkylidyne W(C t Bu)(CH 2 t Bu)(O-2,6- i - Pr 2 C 6 H 3 ) 2 ). Characterized by NMR studies and nuclear Overhauser effect spectroscopy, complex 6 ) with 1 equiv of an yne-ol proligand ( 5 ). Characterized by NMR studies and nuclear Overhauser effect spectroscopy, complex 7 is a dimer. Each metal center contains a tungsten-carbon triple bond tethered to the metal center via an alkoxide ligand. The polymerization of the strained cycloalkyne 3,8-didodecyloxy-5,6-dihydro-11,12-didehydrodibenzo[ a , e ]-[8]annulene, 8 , to generate cyclic polymers was demonstrated. Size exclusion chromatography (SEC) and intrinsic viscosity (η) measurements confirm the polymer's cyclic topology.

This study investigated the effects of aseptic inflammation and heavy metal exposure on immune responses, as well as the potential immunomodulatory properties of the newly synthesized 1-[1-(2,5-dimethoxyphenyl)-4-(naphthalene-1-yloxy)but-2-ynyl]-4-methylpiperazine complexed with β-cyclodextrin (β-CD). Aseptic inflammation was induced by a subcutaneous injection of turpentine in rats, while heavy metal exposure was achieved through a daily administration of cadmium chloride and lead acetate. The levels of immune cell populations, including cytotoxic T lymphocytes (CTL), monocytes, and granulocytes, were assessed in the spleen. The results showed that aseptic inflammation led to decreased levels of CTL, monocytes, and granulocytes on the 14th day, indicating an inflammatory response accompanied by a migration of effector cells to the inflamed tissues. The exposure to cadmium chloride and lead acetate resulted in systemic immunotoxic effects, with reduced levels of B cells, CD4 + Th cells, monocytes, and granulocytes in the spleen. Notably, piperazine complexed with β-CD (the complex ) exhibited significant stimulatory effects on CD4 + , CD8 + , and myeloid cell populations during aseptic inflammation, even in the presence of heavy metal exposure. These findings suggest the potential immunomodulatory properties of the complex in the context of aseptic inflammation and heavy metal exposure.

Antimicrobial resistance is a leading mortality factor worldwide. Here, we report the discovery of clovibactin, an antibiotic isolated from uncultured soil bacteria. Clovibactin efficiently kills drug-resistant Gram-positive bacterial pathogens without detectable resistance. Using biochemical assays, solid-state nuclear magnetic resonance, and atomic force microscopy, we dissect its mode of action. Clovibactin blocks cell wall synthesis by targeting pyrophosphate of multiple essential peptidoglycan precursors (C 55 PP, lipid II, and lipid III WTA ). Clovibactin uses an unusual hydrophobic interface to tightly wrap around pyrophosphate but bypasses the variable structural elements of precursors, accounting for the lack of resistance. Selective and efficient target binding is achieved by the sequestration of precursors into supramolecular fibrils that only form on bacterial membranes that contain lipid-anchored pyrophosphate groups. This potent antibiotic holds the promise of enabling the design of improved therapeutics that kill bacterial pathogens without resistance development., Competing Interests: Declaration of interests The following authors, A.J.P., C.A., A.N., A.L.S., L.L.L., D.H., and K.L., declare competing financial interests because they are employees and consultants of NovoBiotic Pharmaceuticals. A patent US 11,203,616 B2 was issued on 12/21/2021 and describes the use of clovibactin (Novo29) and as an antibiotic, as well as the pharmaceutical composition and antibiotic use of derivatives., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Studying the structural aspects of proteins within sub-cellular compartments is of growing interest. Dynamic nuclear polarization supported solid-state NMR (DNP-ssNMR) is uniquely suited to provide such information, but critically lacks the desired sensitivity and resolution. Here we utilize SNAPol-1, a novel biradical, to conduct DNP-ssNMR at high-magnetic fields (800 MHz/527 GHz) inside HeLa cells and isolated cell nuclei electroporated with [ 13 C, 15 N] labeled ubiquitin. We report that SNAPol-1 passively diffuses and homogenously distributes within whole cells and cell nuclei providing ubiquitin spectra of high sensitivity and remarkably improved spectral resolution. For cell nuclei, physical enrichment facilitates a further 4-fold decrease in measurement time and provides an exclusive structural view of the nuclear ubiquitin pool. Taken together, these advancements enable atomic interrogation of protein conformational plasticity at atomic resolution and with sub-cellular specificity., Competing Interests: The authors have no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Solid-state NMR (ss-NMR) is a powerful tool to investigate noncrystallizable, poorly soluble molecular systems, such as membrane proteins, amyloids, and cell walls, in environments that closely resemble their physical sites of action. Rotational-echo double resonance (REDOR) is an ss-NMR methodology, which by reintroducing heteronuclear dipolar coupling under magic angle spinning conditions provides intramolecular and intermolecular distance restraints at the atomic level. In addition, REDOR can be exploited as a selection tool to filter spectra based on dipolar couplings. Used extensively as a spectroscopic ruler between isolated spins in site-specifically labeled systems and more recently as a building block in multidimensional ss-NMR pulse sequences allowing the simultaneous measurement of multiple distances, REDOR yields atomic-scale information on the structure and interaction of proteins. By extending REDOR to the determination of 1 H-X dipolar couplings in recent years, the limit of measurable distances has reached ~15-20 Å, making it an attractive method of choice for the study of complex biomolecular assemblies. Following a methodological introduction including the most recent implementations, examples are discussed to illustrate the versatility of REDOR in the study of biological systems.

Modular trans-acyltransferase polyketide synthases (trans-AT PKSs) are enzymatic assembly lines that biosynthesize complex polyketide natural products. Relative to their better studied cis-AT counterparts, the trans-AT PKSs introduce remarkable chemical diversity into their polyketide products. A notable example is the lobatamide A PKS, which incorporates a methylated oxime. Here we demonstrate biochemically that this functionality is installed on-line by an unusual oxygenase-containing bimodule. Furthermore, analysis of the oxygenase crystal structure coupled with site-directed mutagenesis allows us to propose a model for catalysis, as well as identifying key protein-protein interactions that support this chemistry. Overall, our work adds oxime-forming machinery to the biomolecular toolbox available for trans-AT PKS engineering, opening the way to introducing such masked aldehyde functionalities into diverse polyketides., (© 2023 Wiley-VCH Verlag GmbH.)

Cancer cells make extensive use of the folate cycle to sustain increased anabolic metabolism. Multiple chemotherapeutic drugs interfere with the folate cycle, including methotrexate and 5-fluorouracil that are commonly applied for the treatment of leukemia and colorectal cancer (CRC), respectively. Despite high success rates, therapy-induced resistance causes relapse at later disease stages. Depletion of folylpolyglutamate synthetase (FPGS), which normally promotes intracellular accumulation and activity of natural folates and methotrexate, is linked to methotrexate and 5-fluorouracil resistance and its association with relapse illustrates the need for improved intervention strategies. Here, we describe a novel antifolate (C1) that, like methotrexate, potently inhibits dihydrofolate reductase and downstream one-carbon metabolism. Contrary to methotrexate, C1 displays optimal efficacy in FPGS-deficient contexts, due to decreased competition with intracellular folates for interaction with dihydrofolate reductase. We show that FPGS-deficient patient-derived CRC organoids display enhanced sensitivity to C1, whereas FPGS-high CRC organoids are more sensitive to methotrexate. Our results argue that polyglutamylation-independent antifolates can be applied to exert selective pressure on FPGS-deficient cells during chemotherapy, using a vulnerability created by polyglutamylation deficiency., (© 2023 van der Krift et al.)

The complex formation between daclatasvir and γ-CD or heptakis(2,3,6-tri-O-methyl)-β-CD (TM-β-CD) was studied by isothermal titration calorimetry and molecular modeling. Both techniques supported the predominant formation of a 2:1 complex in case of γ-CD although a 1:1 complex may be formed to a much lower extent as well. In case of TM-β-CD the stoichiometry of the complex was exclusively 1:1. Complex formation with γ-CD did not require dissociation of the daclatasvir dimer, which is present in solution, and resulted in a complex with a binding constant of 1.67·10 7  M -2 . In contrast, formation of the weak TM-β-CD complex (K = 371 M -1 ) required dissociation of the daclatasvir dimer. This is in line with the observation that the complex formation in case of γ-CD is enthalpy-driven, while the process is entropy-driven in case of TM-β-CD. It is concluded that the plateau observed in capillary electrophoresis is primarily based on the slow dissociation of the daclatasvir-CD complexes caused by steric constrains due to the folded terminal amino acid moieties of daclatasvir exerting a clip effect. In case γ-CD the thermodynamic stability might contribute to the overall slow dissociation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Metal-organic frameworks (MOFs) have been reported as promising materials for electrochemical applications owing to their tunable porous structures and ion-sieving capability. However, it remains challenging to rationally design MOF-based electrolytes for high-energy lithium batteries. In this work, by combining advanced characterization and modeling tools, a series of nanocrystalline MOFs is designed, and the effects of pore apertures and open metal sites on ion-transport properties and electrochemical stability of MOF quasi-solid-state electrolytes are systematically studied. It isdemonstrated that MOFs with non-redox-active metal centers can lead to a much wider electrochemical stability window than those with redox-active centers. Furthermore, the pore aperture of MOFs is found to be a dominating factor that determines the uptake of lithium salt and thus ionic conductivity. The ab initio molecular dynamics simulations further demonstrate that open metal sites of MOFs can facilitate the dissociation of lithium salt and immobilize anions via Lewis acid-base interaction, leading to good lithium-ion mobility and high transference number. The MOF quasi-solid-state electrolyte demonstrates great battery performance with commercial LiFePO 4 and LiCoO 2 cathodes at 30 °C. This work provides new insights into structure-property relationships between tunable structure and electrochemical properties of MOFs that can lead to the development of advanced quasi-solid-state electrolytes for high-energy lithium batteries., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

The FliG protein plays a pivotal role in switching the rotational direction of the flagellar motor between clockwise and counterclockwise. Although we previously showed that mutations in the Gly-Gly linker of FliG induce a defect in switching rotational direction, the detailed molecular mechanism was not elucidated. Here, we studied the structural changes in the FliG fragment containing the middle and C-terminal regions, named FliG MC , and the switch-defective FliG MC -G215A, using nuclear magnetic resonance (NMR) and molecular dynamics simulations. NMR analysis revealed multiple conformations of FliG MC , and the exchange process between these conformations was suppressed by the G215A residue substitution. Furthermore, changes in the intradomain orientation of FliG were induced by changes in hydrophobic interaction networks throughout FliG. Our finding applies to FliG in a ring complex in the flagellar basal body, and clarifies the switching mechanism of the flagellar motor., Competing Interests: The authors declare no competing interests., (© 2023 The Author(s).)

A new difference-spectroscopy method is introduced for measuring T 1 relaxation times. It is inspired by the earlier work of Freeman and Hill and eliminates the need for recording signal intensities at thermodynamic equilibrium. The new method is termed SIP-R (Split-Inversion Pulse and Recovery) and reduces the number of refinable parameters in the curve fitting process of relaxation-delay-dependent signal intensities by using two instead of the three parameters typically used in the standard inversion-recovery sequence. The SIP-R method preserves the dynamic range of measurement of the standard inversion-recovery method but converts the rise-to-maximum mathematical functionality of the recorded data into a decay-to-zero functionality. The decay-to-zero functionality renders the SIP-R sequence advantageous for inverse Laplace transformation numerical optimizations. The new technique proves to be extremely robust with respect to pulse imperfections, pulse-power changes during the pulse sequence, pulse-width miscalibrations, resonance offsets, and radiofrequency field variations. It also compensates for acoustic ring-down effects and proves reliable for measurements with inhomogeneously broadened signals up to several kilohertz linewidth. 1 H NMR experiments with methane gas at pressures up to 50 atm in toroid-cavity pressure vessel probes and in the presence of the methane-to-methanol conversion catalyst Cu-ZnO/Al 2 O 3 are used to show the usefulness of the new method for relaxation time investigations under pressure, at strong radiofrequency field gradients, and in the presence of paramagnetic materials., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The cell wall fulfils several functions in the biology of fungi. For instance, it provides mechanical strength, interacts with the (a)biotic environment, and acts as a molecular sieve. Recently, it was shown that proteins and β-glucans in the cell wall of Schizophyllum commune bind Cu 2+ . We here show that the cell wall of this mushroom forming fungus also binds other (micro-)nutrients. Ca 2+ , Mg 2+ , Mn 2+ , NO 3 - , PO 4 3- , and SO 4 2- bound at levels > 1 mg per gram dry weight cell wall, while binding of BO 3 - , Cu 2+ , Zn 2+ and MoO 4 2- was lower. Sorption of Ca 2+ , Mn 2+ , Zn 2+ and PO 4 that had bound at pH 4, 6, or 8 could be released from the cell wall at pH 4 with a maximum efficiency of 46-93 %. Solid-state NMR spectroscopy showed that the metals had the same binding sites as Cu 3- was promoted at alkaline pH. These compounds as well as BO 3 3- , Cu 2+ , Mg 2+ , NO 3 - , and SO 4 2- that had bound at pH 4, 6, or 8 could be released from the cell wall at pH 4 with a maximum efficiency of 46-93 %. Solid-state NMR spectroscopy showed that the metals had the same binding sites as Cu 2+ when a low concentration of this ion is used. Moreover, data indicate that anions bind to the cell wall as well as to the metal ions. Together, it is shown that the cell wall of S. commune binds various (micro-)nutrients and that this binding is higher than the uptake by hyphae. The binding to the cell wall may be used as a storage mechanism or may reduce availability of these molecules to competitors or prevent toxic influx in the cytoplasm., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

A phenoxathiin-based macrocycle represents an inherently chiral building block, well accessible in two steps from the starting thiacalix[4]arene. The oxidized derivatives bearing one sulfoxide group and three sulfonyl groups were found to exhibit unexpected stereochemical preferences of the sulfoxide group during transformations. The sulfoxide moiety is always pointing out of the cavity (SO out ), while the opposite (SO in ) configuration was never obtained by direct oxidation. In order to achieve full oxidation to sulfone, the configuration of the sulfoxide group must first be changed by a photochemical inversion before the final oxidation occurs. The phenomenon of stereomutation of the sulfoxide group in the thiacalixarene series was studied using a combination of experimental (NMR and single crystal X-ray analysis) and theoretical (DFT) approaches.

Nuclear magnetic resonance (NMR) metabolomics was used for identification of metabolic changes in pancreatic cancer (PC) blood plasma samples when compared to healthy controls or diabetes mellitus patients. An increased number of PC samples enabled a subdivision of the group according to individual PC stages and the construction of predictive models for finer classification of at-risk individuals recruited from patients with recently diagnosed diabetes mellitus. High-performance values of orthogonal partial least squares (OPLS) discriminant analysis were found for discrimination between individual PC stages and both control groups. The discrimination between early and metastatic stages was achieved with only 71.5% accuracy. A predictive model based on discriminant analyses between individual PC stages and the diabetes mellitus group identified 12 individuals out of 59 as at-risk of development of pathological changes in the pancreas, and four of them were classified as at moderate risk.