103,281 results match your criteria hydrogen bond

Unveiling structural, electronic properties and chemical bonding of (VH) (n=10-30) nanoclusters: DFT investigation.

J Mol Graph Model 2021 Mar 24;106:107907. Epub 2021 Mar 24.

State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing, 100029, China. Electronic address:

The geometries, electronic properties, and chemical bonding of (VH) (n=10-30) nanoclusters are systematically investigated by a combination of artificial bee colony optimization with density functional theory calculations. Structure analysis indicates that the structures of (VH) nanoclusters tend to be a disorder, where the hydrogen atoms prefer to occupy the hollow sites among different V atoms, binding three V atoms to form the HV moieties. The bond length suggests that the average V-V bond lengths are about 2. Read More

View Article and Full-Text PDF

Polypyrrole and enzyme free cholesterol flakes based composite: Selective determination of theophylline.

J Pharm Biomed Anal 2021 Apr 6;199:114065. Epub 2021 Apr 6.

Polymer Electronics Lab, Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi, 630 003, Tamil Nadu, India. Electronic address:

In the present work, we demonstrated the non-enzymatic theophylline (TP) detection using nanostructured Polypyrrole (Ppy) and Cholesterol (Ch) flakes coordinated nanocomposite coated on Glassy Carbon Electrode. The higher active surface area and good mechanical stability of the Ppy integrated Ch composite exhibited better oxidation towards TP. The electron transfer across hydrogen bonding is of fundamental importance in enhancing the biochemical process in this biosensor system. Read More

View Article and Full-Text PDF

Essential oils as an effective alternative for the treatment of COVID-19: Molecular interaction analysis of protease (M) with pharmacokinetics and toxicological properties.

J Infect Public Health 2021 Feb 10;14(5):601-610. Epub 2021 Feb 10.

Department of Clinical Pharmacology, College of Medicine, Soonchunhyang University, Cheonan, Republic of Korea. Electronic address:

Background: The current health concern to the entire world is the chronic respiratory disease caused by coronavirus 2 (COVID-19). A specific treatment or proper therapy is still lacking, and the investigations from across the world for proper drug/vaccine development towards disease control are in progress. The Coronavirus replication takes place by the conversion of the polypeptide into functional protein and this occurs due to the key enzyme Main protease (M). Read More

View Article and Full-Text PDF
February 2021

An affinity prediction approach for the ligand of E3 ligase Cbl-b and an insight into substrate binding pattern.

Bioorg Med Chem 2021 Apr 2;38:116130. Epub 2021 Apr 2.

State Key Laboratory of Natural Medicines, and Jiang Su Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China; Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China. Electronic address:

Protein-protein interactions (PPIs) are essentially fundamental to all cellular processes, so that developing small molecule inhibitors of PPIs have great significance despite representing a huge challenge. Studying PPIs with the help of peptide motifs could obtain the structural information and reference significance to reduce the difficulty in the development of small molecules. Computational methods are powerful tools to characterize peptide-protein interactions, especially molecular dynamics simulation and binding free energy calculation. Read More

View Article and Full-Text PDF

Magnetic mesoporous carbon nanosheets derived from two-dimensional bimetallic metal-organic frameworks for magnetic solid-phase extraction of nitroimidazole antibiotics.

J Chromatogr A 2021 Mar 21;1645:462074. Epub 2021 Mar 21.

CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, Gansu 730000, People's Republic of China. Electronic address:

We prepared two-dimensional (2D) bimetallic metal-organic frameworks (Ni-ZIF-8) nanosheets by a simple solvent-free method at room temperature. The morphology and composition of Ni-ZIF-8 can be controlled through adding different amounts of Ni. And then, the 2D magnetic mesoporous nanosheets (Ni/ZnO@C) were synthesized by directly pyrolyzing Ni-ZIF-8 under argon atmosphere and explored as magnetic solid phase extraction (MSPE) adsorbents for the determination of nitroimidazole antibiotics (NIABs). Read More

View Article and Full-Text PDF

Preparation of Artificial Hexaplex Composed of Non-Natural Nucleic Acid.

Curr Protoc 2021 Apr;1(4):e106

Deparment of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Nagoya, Japan.

This article describes synthetic procedures for acyclic D-threoninol nucleic acid tethering of bifacial nucleobases. Because these nucleobases have complementary hydrogen bonding sites on both sides, their oligomers can form a hexaplex. These hexaplexes are suitable for use as metal or pH sensors and as supramolecular motifs. Read More

View Article and Full-Text PDF

Mechanistic Differences of Activation of Rac1 and Rac1.

J Phys Chem B 2021 Apr 13. Epub 2021 Apr 13.

Computer Engineering, Koc University, Rumelifeneri Yolu, 34450 Sariyer, Istanbul, Turkey.

Rac1 is a small GTPase that plays key roles in actin reorganization, cell motility, and cell survival/growth as well as in various cancer types and neurodegenerative diseases. Similar to other Ras superfamily GTPases, Rac1 switches between active GTP-bound and inactive GDP-bound states. Switch I and II regions open and close during GDP/GTP exchange. Read More

View Article and Full-Text PDF

High-Performance Trichloroacetic Acid Sensor Based on the Intramolecular Hydrogen Bond Formation and Disruption of a Specially Designed Fluorescent -Carborane Derivative in the Film State.

ACS Appl Mater Interfaces 2021 Apr 13. Epub 2021 Apr 13.

Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China.

Discriminative and sensitive detection of environmentally important and health-related trichloroacetic acid (TCA) suffers from various problems such as bulky instruments and time-consuming operation as well as complex sample processing. Herein, we present a rapid, sensitive, and specific method for the detection of gaseous TCA using a fluorescent single-molecule array. An -carborane-based benzothiazole derivative (CB-BT-OCH) with specific fluorescence properties was specifically designed and utilized to fabricate a film-based single-molecule array. Read More

View Article and Full-Text PDF

Allosteric communication in DNA polymerase clamp loaders relies on a critical hydrogen-bonded junction.

Elife 2021 Apr 13;10. Epub 2021 Apr 13.

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.

Clamp loaders are AAA+ ATPases that load sliding clamps onto DNA. We mapped the mutational sensitivity of the T4 bacteriophage sliding clamp and clamp loader by deep mutagenesis, and found that residues not involved in catalysis or binding display remarkable tolerance to mutation. An exception is a glutamine residue in the AAA+ module (Gln 118) that is not located at a catalytic or interfacial site. Read More

View Article and Full-Text PDF

Modulation of the Protein-Ligand Interaction in the Presence of Graphene Oxide: a Detailed Spectroscopic Study.

Langmuir 2021 Apr 13. Epub 2021 Apr 13.

Department of Chemistry, Indian Institute of Technology Patna, Bihta, Bihar 801103, India.

Several applications of graphene oxide (GO) have been established over the years, and it has the potential to be used as a biomedical material. Studying the effect of GO on protein-ligand (small molecules/drugs) complex systems are vital as the mechanisms involved are not well understood. The interaction of GO on the protein-ligand binding is also vital for the preparation of an effective drug carrier in the bloodstream. Read More

View Article and Full-Text PDF

Structural basis for an exceptionally strong preference for asparagine residue at the S2 subsite of Stenotrophomonas maltophilia dipeptidyl peptidase 7.

Sci Rep 2021 Apr 12;11(1):7929. Epub 2021 Apr 12.

Department of Science of Technology Innovation, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.

The emergence of drug-resistant bacteria has become a major problem worldwide. Bacterial dipeptidyl peptidases 7 and 11 (DPP7s and DPP11s), belonging to the family-S46 peptidases, are important enzymes for bacterial growth and are not present in mammals. Therefore, specific inhibitors for these peptidases are promising as potential antibiotics. Read More

View Article and Full-Text PDF

Highs and lows of bond lengths: Is there any limit?

Angew Chem Int Ed Engl 2021 Apr 12. Epub 2021 Apr 12.

Universidad Complutense de Madrid, Química Física, SPAIN.

We argue that two distinct points on the potential energy curve (PEC) of a pairwise interaction, the zero-energy crossing point and the point where the stretching force constant vanishes, allow to anticipate the range of possible distances one can expect between two atoms in diatomic, molecular moieties and crystalline systems. We show that these bond stability boundaries are unambiguously defined and correlate with topological descriptors of electron density-based scalar fields, and we put forward a practical method to calculate them easily using generic PECs. Chemical databases and quantum-mechanical calculations are used to analyze a full set of diatomic bonds of atoms from the s-p main block. Read More

View Article and Full-Text PDF

Ultrafine RhNi Nanocatalysts Confined in Hollow Mesoporous Carbons for a Highly Efficient Hydrogen Production from Ammonia Borane.

Inorg Chem 2021 Apr 12. Epub 2021 Apr 12.

Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.

Ammonia borane (AB) has received growing research interest as one of the most promising hydrogen-storage carrier materials. However, fast dehydrogenation of AB is still limited by sluggish catalytic kinetics over current catalysts. Herein, highly uniform and ultrafine bimetallic RhNi alloy nanoclusters encapsulated within nitrogen-functionalized hollow mesoporous carbons (defined as RhNi@NHMCs) are developed as highly active, durable, and selective nanocatalysts for fast hydrolysis of AB under mild conditions. Read More

View Article and Full-Text PDF

Atomistic Modeling of Peptide Aggregation and β-Sheet Structuring in Corn Zein for Viscoelasticity.

Biomacromolecules 2021 Apr 12. Epub 2021 Apr 12.

Whistler Center for Carbohydrate Research, Purdue University, 745 Agricultural Mall Drive, West Lafayette, Indiana 47907, United States.

The structure-function relationships of plant-based proteins that give rise to desirable texture attributes in order to mimic meat products are generally unknown. In particular, it is not clear how to engineer viscoelasticity to impart cohesiveness and proper mouthfeel; however, it is known that intermolecular β-sheet structures have the potential to enhance the viscoelastic property. Here, we investigated the propensity of selected peptide segments within common corn α-zein variants to maintain stable aggregates and β-sheet structures. Read More

View Article and Full-Text PDF

Optimal pH shift of the NADH oxidase from Lactobacillus rhamnosus with a single mutation.

Biotechnol Lett 2021 Apr 12. Epub 2021 Apr 12.

School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China.

Objective: To improve the activity of a water-forming NADH oxidase from Lactobacillus rhamnosus under neutral or alkaline pH for coupling NAD-dependent dehydrogenases with an alkaline optimal pH.

Results: The water-forming NADH oxidase from Lactobacillus rhamnosus was engineered by replacing the aspartic acid or glutamic acid with arginine on the surface. The mutant D251R improved the activity with a 112%, 111%, and 244% relative activity to the wild-type at pH 6. Read More

View Article and Full-Text PDF

Removal of Acid Brown 354 from wastewater by aminized cellulose acetate nanofibers: experimental and theoretical study of the effect of different parameters on adsorption efficiency.

Water Sci Technol 2021 Apr;83(7):1649-1661

Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran 1449614535, Iran.

Wastewater effluents usually involve dyes that are dangerous for aquatic life and other environments. Many of these dyes are toxic, carcinogenic, and can cause skin and eye irritation. In this study, firstly aminized cellulose acetate was prepared from cellulose acetate and applied for the adsorption of Acid Brown 354 from aqueous solutions. Read More

View Article and Full-Text PDF

Crystal structure, hydrogen bonds and thermal transformations of superprotonic conductor Cs(SO)(HPO).

Acta Crystallogr B Struct Sci Cryst Eng Mater 2021 Apr 18;77(Pt 2):266-274. Epub 2021 Mar 18.

Institut Laue-Langevin, 71 Avenue des Martyrs, Grenoble 38042, France.

Crystals of Cs(SO)(HPO) belong to the family of alkali metal acid salts that show a high protonic conductivity at relatively low temperatures. Such properties make superprotonic crystals an excellent choice for the study of the influence of the hydrogen subsystem on the physicochemical properties and promising materials for energy-efficient technologies. Single crystals of Cs(SO)(HPO) were studied by neutron diffraction methods, optical polarization microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Read More

View Article and Full-Text PDF

Synthesis, crystal growth, characterization and DFT investigation of a nonlinear optically active cuminaldehyde derivative hydrazone.

Acta Crystallogr B Struct Sci Cryst Eng Mater 2021 Apr 17;77(Pt 2):249-259. Epub 2021 Mar 17.

School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China.

Single crystals of (E)-N'-(4-isopropylbenzylidene)isonicotinohydrazide monohydrate (IBIHM) were grown from ethanol by the slow evaporation from solution growth technique at room temperature. The structure was elucidated by single-crystal X-ray diffraction analysis and crystallized in the orthorhombic system with noncentrosymmetric space group P222. Optical studies reveal that the absorption was minimum in the visible region and the band-gap energy was estimated using the Kubelka-Munk algorithm. Read More

View Article and Full-Text PDF

Polymorphs of phenazine hexacyanoferrate(II) hydrate: supramolecular isomerism in a 2D hydrogen-bonded network.

Acta Crystallogr B Struct Sci Cryst Eng Mater 2021 Apr 10;77(Pt 2):211-218. Epub 2021 Mar 10.

Department of Chemistry, Faculty of Science, Horvatovac 102a, Zagreb 10000, Croatia.

The crystal structures of two polymorphs of a phenazine hexacyanoferrate(II) salt/cocrystal, with the formula (Hphen)[HFe(CN)][HFe(CN)]·2(phen)·2HO, are reported. The polymorphs are comprised of (Hphen)[HFe(CN)] trimers and (Hphen)[(phen)(HO)][HFe(CN)] hexamers connected into two-dimensional (2D) hydrogen-bonded networks through strong hydrogen bonds between the [HFe(CN)] and [HFe(CN)] anions. The layers are further connected by hydrogen bonds, as well as through π-π stacking of phenazine moieties. Read More

View Article and Full-Text PDF

Chiral Metal Nanoparticle Superlattices Enabled by Porphyrin-Based Supramolecular Structures.

Angew Chem Int Ed Engl 2021 Apr 11. Epub 2021 Apr 11.

Shandong University, School of Chemistry and Chemical Engineering, 27 Shanda Nanlu, 250100, Jinan, CHINA.

Self-assembly is a universal and practical means to create chirality from achiral building blocks. Herein, we show that chiral metal nanoparticle superlattices can be produced through coassembly of achiral metal nanoparticles and porphyrin-based organic molecules. This chirality-transfer from molecules to nanoparticle superstructures across three orders of magnitude in length scale is enabled by the hetero chain-chain van der Waals interactions. Read More

View Article and Full-Text PDF