The mechanism of hydrolysis of the nitrile (N-acetyl-phenylalanyl-2-amino-propionitrile, I) catalyzed by Gln19Glu mutant of papain has been studied by nanosecond molecular dynamics (MD) simulations. MD simulations of the complex of mutant enzyme with I and of mutant enzyme covalently attached to both neutral (II) and protonated (III) thioimidate intermediates were performed. An MD simulation wi...

A theoretical study of the association phenyl and ortho-substituted aryl derivatives lactic acid was carried out. Two variants hydrogen-bonded associates in gas phase were calculated: non-classical, actually found crystals, simulated classical dimers. The energy advantage dimers non-equivalence diastereotopic electron lone pairs at carbonyl oxygen atom shown.

# 2005 International Union of Crystallography Printed in Great Britain ± all rights reserved The crystal structure of l-serine has been determined at room temperature at pressures between 0.3 and 4.8 GPa. The structure of this phase (hereafter termed l-serine-I), which consists of the molecules in their zwitterionic tautomer, is orthorhombic, space group P212121. The least compressible cell dim...

Hydrogen bonding liquids, typically water and alcohols, are known to form labile structures (network, chains, etc...), hence the lifetime of such is an important microscopic parameter, which can be calculated in computer simulations. Since these cluster entities mostly statistical nature, one would expect that, short time regime, their distribution a broad Gaussian-like function time, with sing...

In the planar title mol-ecule, C(16)H(16)N(2)O(4)·C(2)H(6)O, the planar Schiff base molecule is linked to the ethanol solvent mol-ecule by a hydr-oxy-amide hydrogen bond. The hydr-oxy group of the ethanol mol-ecule is a hydrogen-bond donor to the double-bonded N atom of an adjacent Sciff base, pairs of interactions taking place across a center of symmetry and giving rise to a hydrogen-bonded di...

The crystal structures of three salts of anionic 5-aminotetrazole are described. The tetramethylammonium salt (P[Formula: see text]) forms hydrogen-bonded ribbons of anions which accept weak C-H⋯N contacts from the cations. The cystamine salt (C2/c) shows wave-shaped ribbons of anions linked by hydrogen bonds to screw-shaped dications. The tetramethylguanidine salt (P21/c) exhibits layers of an...