90991-90-5Relevant academic research and scientific papers
Modification of an enzyme carboxylate residue in the inhibition of 3-oxo-Δ5-steroid isomerase by (3S)-spiro[5α-androstane-3,2'-oxirane]-17β-ol. Implications for the mechanism of action
Bevins,Bantia,Pollack,et al.
, p. 4957 - 4962 (1984)
The affinity label (3S)-spiro[5α-androstane-3,2'-oxirane]-17β-ol (1β) inhibits 3-oxo-Δ5-steroid isomerase with a stoichiometry of one molecule of inhibitor to one enzyme monomer. The trypsin digest of the inhibited enzyme shows two distinct steroid-bound peptides, both of which are derived from residues 14-45 of the enzyme. The two modified peptides (TPS1 and TPS2) were isolated by HPLC, and each was shown to have an ester bond linking the steroid to the peptide fragment. Hydrolysis of each of the two peptide-steroid adducts releases a different steroid. TPS1 gives 3α-(hydroxymethyl)-5α-androstane-3β,17β-diol (S1) whereas TPS2 releases 3β-(hydroxymethyl)-5α-androstane-3α,17β-diol (S2). Tracer studies with 18O-labeled 1β show the carboxylate residue(s) involved in the ester linkages to be located on the α-face of the bound steroid. Implications of this result for the catalytic mechanism are discussed.
