Formation of a covalent intermediate between alpha-chymotryspin and the B-chain of insulin during enzyme-catalyzed hydrolysis.
Biochim Biophys Acta, 1975/6/24;391(2):410-4.
PMID: 238603
Abstract
The reaction between alpha-chymotrypsin (EC 3.3.21.1) and the B-chain of bovine insulin was studied radiochemically, by using the 3 5S-labelled sulfo B-chain. After incubation at pH 8.0, interrupted by the addition of trichloroacetic acid, a radioactive product was isolated from the reaction mixture. The labelled product was eluted in parallel with the enzyme in gel chromatography, and its properties at different H+ concentrations indicated that chemically it was an ester, i.e. a covalent enzyme-substrate intermediate. No interaction between sulfo beta-chain and alpha-chymotrypsinogen or phenyl-methyl sulfonyl fluoride-inhibited alpha-chymotrypsin was obtained during identical conditions.
MeSH terms
Binding Sites; Chromatography, Gel; Chymotrypsin; Drug Stability; Hydrogen-Ion Concentration; Insulin; Kinetics; Oxidation-Reduction; Protein Binding; Sulfur Radioisotopes
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