Conversion of 1-benzoylindole by Aspergillus strains.

Biotransformation of 1-benzoylindole (BI) by the strains Aspergillus flavus VKM F-1024 and Aspergillus oryzae VKM F-44 was studied. The major metabolites isolated were identified as 4-hydroxyindole (4-HI), 5-hydroxyindole (5-HI), 4-hydroxy- -benzoylindole, 4-hydroxy-1-(4'-hydroxy)-benzoylindole and indole. The structure of the metabolites was determined by mass spectrometry and proton nuclear magnetic resonance spectroscopy.

Kinetic model for the regulation of redox reaction in steroid transformation by Arthrobacter globiformis cells.

A kinetic model of hydrocortisone transformation was developed in studies of the kinetics of biochemical systems. The regulatory bases of the model are the biosynthesis of steroid-transforming enzymes and their activity, the level of endogenous substrates, the respiratory chain activity, and the initial concentrations of reagents. When compared, the experimental data completely coincide with the results of the computer modeling, the coincidence being not only qualitative but also quantitative.

Kinetic model of hydrocortisone 1-en-dehydrogenation by Arthrobacter globiformis.

A kinetic model of the hydrocortisone-to-prednisolone transformation by Arthrobacter globiformis is constructed using the experimental data obtained in studies of this process. Besides adequately describing experimental data, the model allows one to determine the relation between hydrocortisone oxidation and the level of endogenous substrates in bacterial cells, and the relation between the saturating concentration of hydrocortisone in the enzymic system of bacteria and the content of endogenous substrates in their cells, as well as the regulation of the transmembrane potential and the activation by the uncouplers.

Regulation of 3-ketosteroid-1-en-dehydrogenase activity of Arthrobacter globiformis cells by a respiratory chain.

It has been shown that 3-ketosteroid-1-en-dehydrogenase localized in a cytoplasmic membrane donates reducing equivalents to a respiratory chain directly which passes them over to oxygen. Microbial hydrocortisone oxidation is coupled with energy generation in the form of the H+ transmembrane potential. Electron transfer via a respiratory chain is the limiting stage in the process of hydrocortisone 1-en-dehydrogenation.

Redox reactions in hydrocortisone transformation by Arthrobacter globiformis cells.

Hydrocortisone and prednisolone transformation by Arthrobacter globiformis cells in aerobic and anaerobic conditions was studied. 3-Ketosteroid-1-en-dehydrogenase activity was shown to be the major factor regulating the direction of transformation. When it is high (aerobic conditions), the end products of hydrocortisone transformation are prednisolone or its 20 beta-hydroxy derivative.