title: Studies on the molecular mechanism of mersalyl and 4-aminophenylmercuric acetate re-activation of trypsin-thiol complexes.
abstract: 1. Trypsin has been reacted with dithiothreitol and with a naturally occurring thiol-containing trypsin inhibitor to form enzyme-inhibitor complexes. This complex formation is known to be via a reversible intermolecular disulphide linkage. 2. These latent forms of trypsin have been re-activated with mersalyl [N-(O-carboxymethylsalicyloyl)-3-hydroxymercuric-2-methoxypropylamine], 4-aminophenylmercuric acetate and with cystine. 3. Active-site titration analysis of trypsin in the presence of incremental additions of dithiothreitol demonstrated the simultaneous inhibition and modification of the enzyme active site, demonstrating a direct involvement of a significant disulphide controlling the conformation of the active site of the enzyme. 4. Mersalyl addition to the dithiothreitol-reduced trypsin resulted in a regain of enzymic activity and a corresponding regain of availability of the active sites for titration. 5. Mersalyl and 4-aminophenylmercuric acetate were shown to re-activate the trypsin-inhibitor complex. 6. A molecular mechanism for the organomercurial re-activation of latent enzymes of this particular type (involving disulphide exchange) has been proposed.
mesh_terms: D001665:Binding Sites; D003553:Cystine; D004229:Dithiothreitol / Q000494:pharmacology*; D004789:Enzyme Activation; D007700:Kinetics; D008634:Mersalyl / Q000494:pharmacology*; D009941:Organomercury Compounds / Q000494:pharmacology*; D010662:Phenylmercuric Acetate / Q000031:analogs & derivatives / Q000494:pharmacology*; D010663:Phenylmercury Compounds / Q000494:pharmacology*; D011485:Protein Binding; D014357:Trypsin / Q000378:metabolism*
chemical_list: D009941:Organomercury Compounds; D010663:Phenylmercury Compounds; D003553:Cystine; D008634:Mersalyl; C010024:4-aminophenylmercuriacetate; D014357:Trypsin; D010662:Phenylmercuric Acetate; D004229:Dithiothreitol