title: Effect of testosterone-estradiol-binding globulin in the enzymic oxidoreduction of 17-oxygenated c19 steroids.
abstract: The effect of both testosterone-estradiol-binding globulin (TeBG) and albumin on enzymic oxidoreduction of four 17-oxygenated C19 steroids by bacterial 17beta-hydroxysteroid:NAD oxidoreductase from Pseudomonas testosteroni was investigated. The decreased yields of products under presence of TeBG were found in both directions of reversible enzymic reaction. This finding was unexpected in the case of enzymic reduction in which the opposite effect could be assumed with respect of high affinity of the product but not the substrate to TeBG. Kinetically, the competition between enzyme and binding protein for the substrate occurs at enzymic oxidation, whereas the mechanism resembling non-competitive inhibition operates in the enzymic reduction.
mesh_terms: D000728:Androgens; D000734:Androstenediols; D000735:Androstenedione; D001609:Beta-Globulins / Q000494:pharmacology*; D002855:Chromatography, Thin Layer; D003687:Dehydroepiandrosterone; D004958:Estradiol / Q000097:blood*; D006913:Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D007700:Kinetics; D008433:Mathematics; D011485:Protein Binding; D011549:Pseudomonas / Q000201:enzymology*; D013739:Testosterone / Q000097:blood*
chemical_list: D000728:Androgens; D000734:Androstenediols; D001609:Beta-Globulins; D013739:Testosterone; D000735:Androstenedione; D003687:Dehydroepiandrosterone; D004958:Estradiol; D006913:Hydroxysteroid Dehydrogenases