In vitro proteolysis of myofibrillar proteins from beef skeletal muscle by caspase-3 and caspase-6.

The objective of the study was to investigate in vitro degradation of myofibrils by caspase-3 or -6. Myofibrillar proteins prepared from beef skeletal muscle were incubated with caspase-3 or -6 at 30 °C for 2 or 12 h, and subsequently, protein degradation was detected. Results showed that caspase-3 and -6 reproduced the degradation patterns of titin and nebulin observed during normal postmortem (PM) aging; however, they only reproduced the 28 kDa fragment derived from troponin-T. Caspase-3 induced only minor degradation of desmin. However, caspase-6 caused increasing degradation of desmin with extended incubation time and produced three degradation fragments (45, 29, and 27 kDa) of which only the 45 kDa fragment has been reported in aged beef. Therefore, caspase-3 or -6 could only reproduce a part of myofibrillar protein degradation or degradation fragments observed in naturally aged meat and may be involved in PM proteolysis of muscle proteins together with other endogenous proteases.