title: Testosterone-induced proton release and inhibition of tryptic hydrolysis of albumin.
abstract: Further investigation of the effect of bound testosterone on the susceptibility of human serum albumin to tryptic hydrolysis has revealed a stimulation of hydrolysis at low binding levels, becoming an inhibition at higher binding levels. The inhibition, but not the stimulation, is associated with a two-stage steroid-induced proton release phenomenon which may involve the cysteine (SH) group and tyrosine residues. Proton release is also induced by Ca2+ and ethanol. The nature of the effect and the influence of Ca2+ suggests that stimulation of hydrolysis is associated with the presence of one molecule of testosterone and inhibition with the presence of 2-5 molecules at a set of sites which are thermodynamically equivalent.
mesh_terms: D002118:Calcium / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000494:pharmacology; D006868:Hydrolysis; D011522:Protons; D012709:Serum Albumin / Q000378:metabolism*; D013739:Testosterone / Q000494:pharmacology*; D014357:Trypsin / Q000378:metabolism; D014361:Trypsin Inhibitors
chemical_list: D011522:Protons; D012709:Serum Albumin; D014361:Trypsin Inhibitors; D000431:Ethanol; D013739:Testosterone; D014357:Trypsin; D002118:Calcium