鯨スイ臓のタンパク分解酵素に関する研究-V : 長須鯨のcationic chymotrypsinの諸性質について

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Some physical and enzymatic properties of purified fin whale cationic chymotrypsin were studied in comparison with those of bovine α-chymotrypsin. The S20, w value was 2.9 S, and the molecular weight was determined as approximately 20, 000. Fin whale cationic chymotrypsin was found to be composed of about 165 amino acids residues. It is noteworthy that a molecule of fin whale cationic chymotrypsin contains only 4 half-cystine residues unlike bovine α-chymotrypsin, which possesses 10 such residues. The isoelectric point of the enzyme was about 7.2 (μ=0.1). The optimum pH for caseinolytic and esterolytic activities were almost the same as that of bovine α-chymotrypsin. The caseinolytic activity of both enzymes was affected by a low concentration of CaCl2, but in markedly different ways. The substrate specificity was similar to that of bovine α-chymotrypsin. No significant differences were noted between fin whale and bovine cationic chymotrypsins in their reactions to synthetic and naturally occurring inhibitors, bivalent cations and other chemical reagents.