Copper-containing nitrite reductases possess a trimeric structure where the catalytic Cu site, located at the monomer-monomer interface, resembles the catalytic sites of a number of Zn enzymes. Nitrite reductase from Alcaligenes xylosoxidans has optimum activity at pH 5.2 which decreases to a negligible level at pH 8. The structure of this nitrite reductase has previously been determined at pH ...

The effects of confinement in carbon nanotubes on Fischer-Tropsch (FT) activity, selectivity and lifetime of Carbon NanoTubes (CNTs) supported iron catalysts are reported. A method was developed to control the position of the catalytic sites on either inner or outer surface of carbon nanotubes. TEM analyses revealed that more than 80% of iron oxide particles can be controlled to be position...

Equilibrium nucleotide binding to the three catalytic sites of Escherichia coli F1-ATPase was measured in the presence of the inhibitors azide, dicyclohexylcarbodiimide, and aurovertin to elucidate mechanisms of inhibition. Fluorescence signals of beta-Trp-331 and beta-Trp-148 substituted in catalytic sites were used to determine nucleotide binding parameters. Azide brought about small decrease...

UNLABELLED The molecular integrity of the active site of phytases from fungi is critical for maintaining phytase function as efficient catalytic machines. In this study, the molecular dynamics (MD) of two monomers of phytase B from Aspergillus niger, the disulfide intact monomer (NAP) and a monomer with broken disulfide bonds (RAP), were simulated to explore the conformational basis of the loss...

Phosphodiesterase-5 (PDE5) is phosphorylated at a single serine residue by cyclic nucleotide-dependent protein kinases. To test for a direct effect of phosphorylation on the PDE5 catalytic site, independent of cGMP binding to the allosteric sites of the enzyme, binding of the catalytic site-specific substrate analog [(3)H]tadalafil to PDE5 was measured. Phosphorylation increased [(3)H]tadalafil...

Promiscuity, the basis for the evolution of new functions through 'tinkering' of residues in the vicinity of the catalytic site, is yet to be quantitatively defined. We present a computational method Promiscuity Indices Estimator (PROMISE)--based on signatures derived from the spatial and electrostatic properties of the catalytic residues, to estimate the promiscuity (PromIndex) of proteins wit...

An artificial phosphodiesterase (1) bearing two kinds of metal binding sites, a catalytic site and a regulatory bipyridine site showed a unique allosteric transition in the catalytic activity against the metal concentration.