The aim of this study was to investigate the dual effect of the nitric oxide donor NOR-3 and calpastatin on µ-calpain activity, autolysis, and proteolytic ability. µ-Calpain and calpastatin were purified and allocated to the following five treatments: µ-calpain, µ-calpain + calpastatin, µ-calpain + NOR-3, µ-calpain + calpastatin + NOR-3, and µ-calpain + NOR-3 + calpastatin. µ-Calpain autolysis and the activity against purified myofibrils was initiated by addition of calcium. Results showed that NOR-3 could induce µ-calpain S-nitrosylation and effectively block the activity via the inhibition of µ-calpain autolysis. Calpastatin inhibited µ-calpain activity in a dose-dependent manner. The combined treatment of NOR-3 and calpastatin exerted a further inhibitory effect on µ-calpain activity, autolysis and proteolysis which was affected by the addition order of NOR-3 and calpastatin. Our data suggest that S-nitrosylation may play a regulatory role in mediating µ-calpain activity in the presence of calpastatin.

这项研究的目的是研究一氧化氮供体NOR-3和钙蛋白酶抑制剂对μ-钙蛋白酶活性，自溶和蛋白水解能力的双重作用。将µ-Calpain和Calpastatin纯化并分配给以下五种处理：µ-calpain，µ-calpain + calpastatin，µ-calpain + NOR-3，µ-calpain + calpastatin + NOR-3和µ-calpain + NOR- 3 +钙抑素。通过添加钙来启动μ-钙蛋白酶的自溶作用和对纯化的肌原纤维的活性。结果表明，NOR-3可以诱导μ-钙蛋白酶的S-亚硝基化，并通过抑制μ-钙蛋白酶的自溶而有效地阻断其活性。钙抑素以剂量依赖性方式抑制μ-钙蛋白酶活性。NOR-3和钙蛋白酶抑制剂的联合治疗对µ-钙蛋白酶活性具有进一步的抑制作用，自溶和蛋白水解受到NOR-3和钙蛋白酶抑制素添加顺序的影响。我们的数据表明，在存在钙蛋白酶抑制素的情况下，S-亚硝基化作用可能在介导μ-钙蛋白酶活性中起调节作用。