Heme coordination state determines the functional diversity of heme proteins. Using myoglobin as a model protein, we designed a distal hydrogen-bonding network by introducing both distal glutamic acid (Glu29) and histidine (His43) residues and regulated the heme into a bis-His coordination state with native ligands His64 and His93. This resembles the heme site in natural bis-His coordinated hem...

Grapevine (Vitis vinifera cv. Touriga) callus cell walls contain a high level of the monomeric extensin, GvP1. Hydrogen peroxide stimulus of these cultures causes the rapid loss of monomeric GvP1, concomitant with marked increases in insoluble GvP1 amino acids and wall resistance to digestion by fungal lytic enzymes. JIM11 immunolocalization studies indicated that monomeric and network GvP1 wer...

In the crystal structure of the title compound, C(5)H(6)N(3)O(2) (+)·H(2)PO(4) (-), the dihydrogen phosphate anions are linked through short O-H⋯O hydrogen bonds, forming infinite double chains running parallel to the b axis. Centrosymetric N-H⋯O hydrogen-bonded cationic dimers form bridges between these chains by means of inter-molecular N-H⋯O and O-H⋯O hydrogen bonds, leading to a two-dimensi...

Enzymes use protein architectures to create highly specialized structural motifs that can greatly enhance the rates of complex chemical transformations. Here, we use experiments, combined with ab initio simulations that exactly include nuclear quantum effects, to show that a triad of strongly hydrogen-bonded tyrosine residues within the active site of the enzyme ketosteroid isomerase (KSI) faci...

The asymmetric unit of the title co-crystal salt, 1H-imidazol-3-ium 2,4,6-tri-nitro-phenolate monohydrate, C4H7N2+·C6H2N3O7-·H2O, contains one imidazolium cation, one picrate anion and one solvent water mol-ecule of crystallization. The phenolic proton has been transferred to an imidazole N atom. In the crystal, the components are linked by N-H⋯O and O-H⋯O hydrogen bonds into a three-dimensiona...

The solubility of hydrogen in amorphous silica at a temperature of 250 °C and pressures up to 75 kbar is studied using a quenching technique. The molar ratio H(2)/SiO(2) is found to linearly increase with pressure from X = 0.16 at P = 6 kbar to X = 0.53 at P = 75 kbar. An investigation of a sample with X = 0.47 by Raman spectroscopy demonstrated that hydrogen dissolves in silica in the form of ...

Infrared plus vacuum ultraviolet (IR + VUV) photoionization vibrational spectroscopy of 2-butanone/methanol clusters [MEK·(MeOH)n, n = 1-4] is performed to explore structures associated with hydrogen bonding of MeOH molecules to the carbonyl functional group of the ketone. IR spectra and X3LYP/6-31++G(d,p) calculations show that multiple isomers of MEK·(MeOH)n are generated in the molecular bea...

A charge-assisted hydrogen-bonding network involving N-H⋯O and O-H⋯O hydrogen bonds stabilizes the crystal of the title salt, C5H8N3 (+)·H2PO4 (-). The dihydrogen phosphate anions form one-dimensional chains along [100], via O-H⋯O hydrogen bonds. The 2-amino-4-methyl-pyrimidinium cations are linked to these chains by means of two different kinds of N-H⋯O hydrogen bonds. Neighbouring chains are ...

Rubidium hydrogen carbonate, RbHCO3, features an order/disorder phase transition at TC = 245 K from the high-temperature (HT) disordered C2/m modification to the low-temperature (LT) C-1 modification. The crystal structures are characterized by [HCO3]22- pairs of hydrogen carbonate groups connected by strong hydrogen bonding. The [HCO3]22- pairs are connected by Rb+ cations into a three-dimensi...

Multiple-quantum nuclear-magnetic-resonance techniques are used to study the distribution of hydrogen in hydrogenated amorphous silicon. Using the fact that multiple-quantum excitation is limited by the size of the dipolar-coupled spin system, we show that the predominant bonding environment for hydrogen is a cluster of four to seven atoms. For device-quality films, the concentration of these c...