Effect of heat shock protein 27 on the <i>in vitro</i> degradation of myofibrils by caspase‐3 and μ‐calpain

Abstract

Summary This study was designed to investigate the effect of heat shock protein 27 ( HSP 27) on the in vitro degradation of myofibrils induced by caspase‐3 or μ‐calpain. Myofibrillar proteins were prepared from at‐death beef muscles and incubated with caspase‐3 or μ‐calpain with and without HSP 27, or with HSP 27 alone, at 30 °C for 2 h, and protein degradation was assessed. Results showed that caspase‐3 promoted the degradation of titin, nebulin and troponin‐T, and μ‐calpain promoted the degradation of nebulin, desmin and troponin‐T, observed during normal PM ageing. Moreover, the addition of HSP 27 restricted the degradation of troponin‐T in μ‐calpain‐ and caspase‐3‐treated myofilaments, and restricted the degradation of desmin in μ‐calpain‐treated myofilaments. Therefore, HSP 27 may indirectly or directly interact with caspase‐3 and μ‐calpain, reducing their activity and mediating PM proteolysis of muscle proteins to affect meat tenderisation.