We have generated 3 ns molecular dynamic (MD) simulations, in aqueous solution, of the bacterial soluble glucose dehydrogenase enzyme.PQQ.glucose complex and intermediates formed in PQQ reduction. In the MD structure of enzyme.PQQ.glucose complex the imidazole of His144 is hydrogen bonded to the hydroxyl hydrogen of H[bond]OC1(H) of glucose. The tightly hydrogen-bonded triad Asp163-His144-gluco...

In the title compound, C(12)H(12)N(2)O(2)S, there are S-H⋯N and N-H⋯O hydrogen-bond inter-actions. The N-H⋯O hydrogen bond is bifurcated, with the hydrogen being simultaneously donated to two equivalent O atoms, forming one intra- and one inter-molecular N-H⋯O bond with an R(1) (2)(4) motif. The motif of the S-H⋯N hydrogen bond is R(2) (2)(12).

Water plays an important role in the stability of minerals containing the deca and hexavanadates ions. A selection of minerals including pascoite, huemulite, barnesite, hewettite, metahewettite, hummerite has been analysed. Infrared spectroscopy combined with Raman spectroscopy has enabled the spectra of the water HOH stretching bands to be determined. The use of the Libowitsky type function al...

The theorem of matching proton affinities (PA) has been widely used in the analysis of hydrogen bonds. However, most experimental and theoretical investigations have to cope with the problem that the variation of the PA of one partner in the hydrogen bond severely affects the properties of the interface between both molecules. The B3LYP/d95+(d,p) analysis of two hydrogen bonds coupled by a 5-me...

A new approach is presented for determining the rigid regions in proteins and the flexible joints between them. The short-range forces in proteins are modeled as constraints and we use a recently developed formalism from graph theory to analyze flexibility in the bond network. Forces included in the analysis are the covalent bond-stretching and bond-bending forces, salt bridges, and hydrogen bo...

The mononuclear mixed-ligand title complex, [CuCl(C7H7N3O2S)(C18H15P)2], displays a distorted tetra-hedral coordination sphere around the CuI atom, with two P atoms from two tri-phenyl-phosphane mol-ecules, one terminal S atom from a 1-(4-nitro-phen-yl)thio-urea mol-ecule and a chloride ion as ligands. An intra-molecular N-H⋯Cl hydrogen bond stabilizes the mol-ecular conformation [graph-set mot...

Deuterated medicinal chemistry is an attempt to introduce deuterium into existing drug molecules through the replacement of hydrogen atoms (-H) with (-D). The process deuteration reduce rates breaking carbonhydrogen bond. If carbon-hydrogen bond rate-determining step in biotransformation drug, deuterated may show improved pharmacokinetic characteristics, such as a longer half-life, hence loweri...

Evidence from proteins and peptides supports the conclusion that intrapeptide hydrogen bonds stabilize the folded form of proteins. Paradoxically, evidence from small molecules supports the opposite conclusion, that intrapeptide hydrogen bonds are less favorable than peptide-water hydrogen bonds. A related issue-often lost in this debate about comparing peptide-peptide to peptide- water hydroge...

Extended hydrogen bond networks are a common structural motif of enzymes. A recent analysis proposed quantum delocalization of protons as a feature present in the hydrogen bond network spanning a triad of tyrosines (Y(16), Y(32), and Y(57)) in the active site of ketosteroid isomerase (KSI), contributing to its unusual acidity and large isotope shift. In this study, we utilized amber suppression...