CALPAIN-II-LIKE PROTEINASE OF SCALLOP (PATINOPECTEN-YESSOENSIS) STRIATED ADDUCTOR MUSCLE

1. A Ca2+-dependent cysteine proteinase was purified from scallop striated adductor muscle by ammonium sulfate fractionation and column chromatography on DEAE-cellulose and Sephacryl S-300. 2. The enzyme is of M(r) approximately 200,000, composed of two M(r) 100,000 subunits. 3. The enzyme is a cysteine proteinase with optimum activity at pH 6.8 and about 18-degrees-C. In addition, it requires 1.7 mM Ca2+ for half-maximal activity and more than 10 mM Ca2+ for maximal activity. Thus the enzyme can be classified as calpain II.