Abstract:  Calpain 3 is a skeletal muscle-specific calpain in calpain family. Isolation of the intact 94kDa enzyme has been difficultto achieve due to its rapid autolysis, and uncertainty has arisen over its dependence for Ca2+ activity.In the study, calpain3 crudeextract was obtiained, and found that in the presence of Ca2+, calpain3 cleaved itself into several fragments. This indicated thatthe autolysis of calpain3 was dependent on the concentration of Ca2+. It was also found that the autolysis of calpain3 proceedsin four consecutives steps: 89, 68and 58kDa fragments are produced as intermediates before a stable 55kDa fragment appears.

Key words: calpain3, autolysis, calcium