Exploring the Effects of S‑Nitrosylation on\nCaspase‑3 Modification and Myofibril Degradation of Beef In\nVitro

This\nstudy aimed to explore the effects of S-nitrosylation on caspase-3\nmodification and its subsequent effects on beef myofibril degradation\nin vitro. Recombinant caspase-3 was reacted with different concentrations\nof S-nitrosoglutathione (GSNO, nitric oxide donor) at 37 °C for\n30 min and subsequently incubated with purified myofibrillar protein\nfrom bovine <i>semimembranosus</i> muscle. Results indicated\nthat the activity of caspase-3 was significantly reduced after GSNO\ntreatments (<i>P</i> < 0.05) and showed a dose-dependent\ninhibitory effect, which was attributed to the increased S-nitrosylation\nextent of caspase-3. LC–MS/MS analysis revealed that caspase-3\nwas S-nitrosylated at cysteine sites 116, 170, 184, 220, and 264.\nMoreover, the degradation of desmin and troponin-T was notably suppressed\nby S-nitrosylated caspase-3 (<i>P</i> < 0.05). To conclude,\nprotein S-nitrosylation could modify the cysteine residues of caspase-3,\nwhich accounts for the reduced caspase-3 activity and further represses\nits proteolytic ability on beef myofibrillar protein.