Effect of Storage on the Changes in Cathepsin D Activity, Nucleotide Contents, Peptide Profiles and Muscle Ultrastructure of Aristichthys Nobilis, R

Abstract

Cathepsin D from the muscle of bighead carp (Aristichthys no bilis, R.)was extracted ,purified and partially characterized . The extract ion and purification o f the enzyme was achieved byautolysis of the muscle,acetone precipitation, gelfiltrat ion on Sephadex G100-120 and on ionexchange carboxymethyl cellulose (CMC)column chromatography . It had a molecular weight(m.w)of 37,500-38,000 dalton (D) with a pH optimum at 3.2 and temperature optimum of 50°C. Myofibril was also optimally digested at pH3.2. The purified enzyme had a single major peptideband on sodiumdodecyl sulfate polyacrylamide gelelectrophoresis SDS-PAGE )and was completely inhibited by pepstatin .