Inhibition of creatine kinase by S-nitrosoglutathione

The sarcoplasmic reticulum-bound creatine kinase from rabbit skeletal muscle was inhibited by the nitric oxide donor S-nitrosoglutathione (GSNO), This led to a decrease in Ca2+ uptake in sarcoplasmic reticulum vesicles when the transport was driven by ATP generated from phosphocreatine and ADP. In contrast, the Ca2+ transport measured using 2 mM ATP as substrate was unaffected by GSNO up to 200 mu M. GSNO (5-20 mu M) inhibited the activity of both soluble and membrane-bound creatine kinase, Oxyhemoglobin (15-40 mu M) protected creatine kinase against inactivation by GSNO, The inhibition by 10 mu M GSNO was reversed by the addition of dithiothreitol (2 mM). The results indicate that nitric oxide (NO, including NO+, NO and NO-) inactivates creatine kinase in vitro by promoting nitrosylation of critical sulphydryl groups of the enzyme.