PubMed Health⌕ Search

Biomedical subjects

R J Mehta

Publications and source records attributed to R J Mehta.

29 records · Page 2Linked to original sources
PubMed1977

Mannitol oxidation in two Micromonospora isolates and in representative species of other actinomycetes.

Mannitol kinase and mannitol-1-phosphate dehydrogenase activities were detected in two Micromonospora isolates. The presence of these enzyme activities indicates that mannitol is catabolized first to mannitol-1-phosphate and then to fructose-6-phosphate. Mannitol-oxidizing enzymes were also surveyed in representative species of four other genera of actinomycetes. Mannitol-1-phosphate dehydrogenase was detected in cell-free extracts of Streptomyces lactamdurans. In contrast, cell-free extracts of Mycobacterium smegmatis, Nocardia erythrophila, Streptomyces lavendulae, and Actinoplanes missouriensis contained mannitol dehydrogenase activity but no detectable mannitol-1-phosphate dehydrogenase activity. The mannitol dehydrogenase activities in the latter species support the operation of a pathway for catabolism of mannitol that involves the oxidation of mannitol to fructose, followed by phosphorylation to fructose-6-phosphate.

Actinomycetales↗
PubMed1977

Methylamine dehydrogenase from the obligate methylotroph Methylomonas methylovora.

An obligate methyltroph Methylomonas methylovora oxidized methylamine, formaldehyde, and formate. Enzymes oxidizing these substrates were detected in a cell-free system. Phenazine methosulfate-linked methylamine dehydrogenase was purified 21-fold. The enzyme had optimum activity at pH 7.5 and was stable at 60 degrees C for 5 min. The enzyme activity was inhibited by parachloromercuric benzoate, isonicotinic acid hydrazide, mercuric chloride, and sodium borate.

Aldehyde Oxidoreductases↗
PubMed1975

A novel inducible formaldehyde dehyrogenase of Pseudomonas sp. (RJ1).

A novel, pyridine-nucleotide-independent, inducible formaldehyde dehydrogenase acitivity was detected in cells of Pseudomonas sp. (RJ1) propagated on methylamine and oxalated. The pH optimum of the dehydrogenase was 7.0. Dichlorophenol-indophenol or potassium ferricyanide served as an electron acceptor. The rate of reduction of these electron acceptors was shown to be stimulated by phenazine methosulfate. The dehydrogenase was inhibited by parahydroxymercuric benzoate and iodoacetamide. This inhibition suggests that the enzyme contains sulfhydryl groups. The stoichiometry of the reaction in terms of oxygen uptake to formate formation was 0.5, which agrees with the theoretical value.

2,6-Dichloroindophenol↗
PubMed1975

Pyridine nucleotide-linked oxidation of methanol in methanol-assimilating yeasts.

An alcohol dehydrogenase linked to nicotinamide adenine dinucleotide and requiring glutathione has been isolated and partially purified from two methanol-assimilating yeasts. It differs from previously described methanol-oxidizing enzymes in pH optima, electron acceptor specificity, substrate specificity, inhibition pattern, and stability.

Alcohol Oxidoreductases↗
PubMed1972

New obligate methylotroph.

A new and unique obligate methylotroph was isolated from enrichment cultures with methanol as the sole source of carbon and energy. The organism grows only on methanol and methylamine and not on methane. It does not have a complex intracellular membrane system. (14)C-acetate was assimilated by growing cultures and cell suspensions but was incorporated into only a limited number of cell constituents. (14)C-acetate incorporation was strictly dependent on the oxidation of methanol or methylamine as a source of energy. Extracts had relatively low levels of enzymes of the tricarboxylic acid cycle, and alpha-ketoglutarate dehydrogenase was not detected. Comparisons were made with a facultative methylotroph isolated from the same enrichment cultures. The new obligate methylotroph contained hexose phosphate synthetase, a key enzyme in the ribose phosphate cycle of methyl metabolism.

Acetates↗