Chymotrypsin Inhibitor from the Top Shell Muscle

Abstract

A chymotrypsin inhibitor was extracted from the top shell muscle, and purified by ammonium sulfate fraction, ion exchange chromatography, gel feltration, and affinity chromatography. Three active components (F-I, F-II, and F-III) were found. The main fraction (F-III) was purified 483-fold with recovery of 7.95%. The molecular weight of the inhibitor was estimated to be 41, 000 by gel filtration or 43, 000 by SDS-polyacrylamide gel electrophoresis, and its isoelectric point was found to be pH 3.7 to 3.8. The inhibitor was active toward α-, β-, γ-, and δ-chymo-trypsins. The type of inhibition was competitive for α-chymotrypsin, but noncompetitive for trypsin. One mol of the inhibitor fromed complex with 1 mol of enzyme. Total amino acid residues were estimated to be 405, and 34 Cys/2 residues were found.