Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Circ Res. 2012 Sep 28;111(8):1002-11. doi: 10.1161/CIRCRESAHA.112.270827. Epub 2012 Jul 31.
In the myocardium, redox/cysteine modification of proteins regulating Ca(2+) cycling can affect contraction and may have therapeutic value. Nitroxyl (HNO), the one-electron-reduced form of nitric oxide, enhances cardiac function in a manner that suggests reversible cysteine modifications of the contractile machinery.
To determine the effects of HNO modification in cardiac myofilament proteins.
The HNO-donor, 1-nitrosocyclohexyl acetate, was found to act directly on the myofilament proteins, increasing maximum force (F(max)) and reducing the concentration of Ca(2+) for 50% activation (Ca(50)) in intact and skinned cardiac muscles. The effects of 1-nitrosocyclohexyl acetate are reversible by reducing agents and distinct from those of another HNO donor, Angeli salt, which was previously reported to increase F(max) without affecting Ca50. Using a new mass spectrometry capture technique based on the biotin switch assay, we identified and characterized the formation by HNO of a disulfide-linked actin-tropomyosin and myosin heavy chain-myosin light chain 1. Comparison of the 1-nitrosocyclohexyl acetate and Angeli salt effects with the modifications induced by each donor indicated the actin-tropomyosin and myosin heavy chain-myosin light chain 1 interactions independently correlated with increased Ca(2+) sensitivity and force generation, respectively.
HNO exerts a direct effect on cardiac myofilament proteins increasing myofilament Ca(2+) responsiveness by promoting disulfide bond formation between critical cysteine residues. These findings indicate a novel, redox-based modulation of the contractile apparatus, which positively impacts myocardial function, providing further mechanistic insight for HNO as a therapeutic agent.
在心肌中，调节 Ca(2+) 循环的蛋白质的氧化还原/半胱氨酸修饰可以影响收缩，并可能具有治疗价值。亚硝酰（HNO）是一氧化氮的单电子还原形式，以提示收缩机制的可逆半胱氨酸修饰的方式增强心脏功能。
确定 HNO 修饰对心肌肌球蛋白蛋白的影响。
发现 HNO 供体 1-硝基亚环己基乙酸酯直接作用于肌球蛋白蛋白，增加最大力（F(max)）并降低完整和去皮心肌中 50%激活 Ca(2+)（Ca(50)）的浓度。1-硝基亚环己基乙酸酯的作用可以通过还原剂逆转，并且与另一种 HNO 供体 Angeli 盐的作用不同，Angeli 盐以前被报道增加 F(max)而不影响 Ca50。使用基于生物素开关测定的新质谱捕获技术，我们鉴定并表征了 HNO 形成的二硫键连接的肌动蛋白-原肌球蛋白和肌球蛋白重链-肌球蛋白轻链 1。1-硝基亚环己基乙酸酯和 Angeli 盐的作用与每个供体诱导的修饰的比较表明，肌动蛋白-原肌球蛋白和肌球蛋白重链-肌球蛋白轻链 1 相互作用分别独立地与增加的 Ca(2+) 敏感性和力产生相关。
HNO 对心肌肌球蛋白蛋白产生直接影响，通过促进关键半胱氨酸残基之间的二硫键形成来增加肌球蛋白对 Ca(2+) 的反应性。这些发现表明了收缩装置的一种新的、基于氧化还原的调节，这对心肌功能产生了积极影响，为 HNO 作为治疗剂提供了进一步的机制见解。
