(6R)-2,2,6-Trimethyl-1,4-cyclohexanedione (levodione) reductase was isolated from a cell extract of the soil isolate Corynebacterium aquaticum M-13. This enzyme catalyzed regio- and stereoselective reduction of levodione to (4R,6R)-4-hydroxy-2,2, 6-trimethylcyclohexanone (actinol). The relative molecular mass of the enzyme was estimated to be 142,000 Da by high-performance gel permeation chroma...

A procedure is described for the purification of bull semen NAD nucleosidase. The enzyme was purified over 400-fold to a final specific activity of 9906 units per mg of protein. A spectrophotometric assay was developed in which the enzyme-catalyzed release of 3-acetylpyridine from d-acetylpyridine adenine dinucleotide was followed by measuring the increase in optical density at 232 mp. At pH 7....

High-resolution carbon-13 nuclear magnetic resonance (NMR) spectra of enzyme-inhibitor and enzyme-substrate complexes provide detailed structural and stereochemical information on the mechanism of enzyme action. The proteases trypsin and papain are shown to form tetrahedrally coordinated complexes and acyl derivatives with a variety of compounds artificially enriched at the site or sites of int...

A procedure is described for the purification of bull semen NAD nucleosidase. The enzyme was purified over 400-fold to a final specific activity of 9906 units per mg of protein. A spectrophotometric assay was developed in which the enzyme-catalyzed release of 3-acetylpyridine from d-acetylpyridine adenine dinucleotide was followed by measuring the increase in optical density at 232 mp. At pH 7....

In this study, a new graphene ceramic composite (GCC) was prepared based on the reduced graphene oxide (rGO) doped in sol-gel derived silica. The GCC was prepared by dispersing rGO nanosheets into the sol-gel precursors containing methyl triethoxysilane, methanol and hydrochloric acid solution. During an acid catalyzed hydrolyze reaction and gelation process, rGO nanosheets were successfully do...

The oxidation reaction was catalyzed by an enzyme that had the following properties: (a) utilization of one molecule of oxygen in a single step, (b) inhibition by catalase, and (c) specific reversal of catalase inhibition by hydrogen peroxide from a donor reaction. Other properties of the enzyme, including cyanide and light reversible CO inhibitions, suggested that it was an iron porphyrin enzy...

Enzyme I of the bacterial phosphoenolpyruvate: sugar phosphotransferase system catalyzes phosphoryl transfer from phosphoenolpyruvate to the heat-stable phosphoryl carrier protein, HPr. Enzyme I also catalyzes a rapid phosphoryl exchange reaction in which the phosphoryl moiety of phosphoenolpyruvate is transferred to pyruvate. Additionally, Enzyme I plus HPr catalyze the slow hydrolysis of pho...

Microsomal enzyme preparations from dog liver, kidney, and bladder were used to assess the prostaglandin H synthase-catalyzed activation of carcinogenic aromatic amines to bind covalently to proteins and nucleic acids. Benzidine, a urinary bladder carcinogen, bound to protein of bladder transitional epithelial and renal inner and outer medullary microsomes and was dependent upon addition of ara...

In situ hydrogelation of injectable precursors upon biological stimulus is relevant to generate hydrogels under mild conditions and, potentially, at a side interest. Here, it shown that hydrolytic enzymes can be used initiate the formation covalent hydrogel networks, realizing cleavage-leading-to-gelation strategy. For this purpose, two-component system used, consisting 4-arm polyethylene glyco...