Regulation of calpain-1 activity and protein proteolysis by protein nitrosylation in postmortem beef

The effects of nitric oxide (NO) and its induced protein nitrosylation on calpain-1 activation and protein proteolysis in beef during postmortem aging were investigated. Five semimembranosus muscles were removed from beef cattle carcass. Beef samples were incubated with one of following treatments for 24 h at 4 degrees C: control (normal saline), NO donor (100, 200 and 400 mu M S-nitrosoglutathione (GSNO)) or nitric oxide synthase (NOS) inhibitor (0.05, 0.1 and 0.15 M N omega-Nitro-L-arginine methyl ester hydrochloride (L-NAME)). After incubation, the beef samples were vacuum-packaged and aged at 4 degrees C for 1, 4, and 7 days. Results showed that GSNO decreased and L-NAME increased the extent of calpain-1 autolysis at d 1. Degradation of desmin and troponin-T was increased by L-NAME while decreased by GSNO. These results suggest that NO could regulate calpain-1 autolysis and its proteolysis activity during postmortem aging in beef SM muscle.