Electron spin resonance study of the role of NO . catalase in the activation of guanylate cyclase by NaN3 and NH2OH. Modulation of enzyme responses by heme proteins and their nitrosyl derivatives.
Electron spin resonance study of the role of NO . catalase in the activation of guanylate cyclase by NaN3 and NH2OH. Modulation of enzyme responses by heme proteins and their nitrosyl derivatives.
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电子自旋共振研究NO的作用。
DOI：
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发表时间：
1979
影响因子：
4.8
通讯作者：
D. Pratt
中科院分区：
文献类型：
--
作者：
P. Craven;F. Derubertis;D. Pratt
NO的作用。用电子自旋共振(ESR)波谱研究了NaN3和NH2 OH激活部分纯化的大鼠肝脏可溶性鸟苷环化酶中的过氧化氢酶。牛肝过氧化氢酶与NO的平衡导致了一个顺磁性物种的形成，其ESR谱与NO类似。过氧化氢酶。这种顺磁性复合体对部分纯化的鸟苷环化酶制剂产生浓度依赖的刺激，这些制剂没有可检测到的内源性血红素含量。NO对部分纯化的鸟苷环化酶的刺激作用。过氧化氢酶活性与NO类似。血红蛋白和NO。用苯巴比妥处理的大鼠肝微粒体与NO反应制备细胞色素P-420。相比之下，这些相同的酶制剂不能单独对NO或过氧化氢酶起作用。在纯化的鸟苷环化酶中加入血红素或血红蛋白以及还原剂，可恢复酶对NO和N-甲基-N‘-硝基-N-亚硝基(MNNG)的反应性，但不能恢复对NaN3或NH_2OH的反应性。对后者的反应由过氧化氢酶恢复，并由过氧化氢产生系统增强。NO.的形成。ESR波谱显示，在含有NaN3或NH2O、过氧化氢酶和葡萄糖-葡萄糖氧化酶、过氧化氢产生系统的测试溶液中，过氧化氢酶复合体明显存在。NO的存在。过氧化氢酶与测试溶液激活纯化鸟苷环化酶的能力有很好的相关性。这些结果为NaN3和NH2OH在导致鸟苷环化酶激活的条件下产生依赖于过氧化氢酶的NO提供了证据。预制号。不管有没有血红蛋白。细胞色素P-420还可激活部分纯化的血红素缺乏的鸟苷环化酶。几个预制种的能力都没有。血红素蛋白复合体，但不是NO，刺激血红素缺乏的鸟苷环化酶，支持顺磁性亚硝酰基的形成的概念。血红素复合体由酶或非酶反应介导，是NO或NO形成化合物激活鸟苷环化酶过程中常见且必不可少的步骤。在没有NO配体的情况下，血红蛋白和过氧化氢酶都抑制相应的NO的刺激作用。鸟苷环化酶上的血红素蛋白。从NO中释放每一种血红素蛋白。在有氧条件下，与无氧条件相比，血红素蛋白复合体出现得更快。然而，作为一种NO的抑制剂，血红蛋白的效果大约是后者的2000倍。血红蛋白对鸟苷环化酶的刺激作用比过氧化氢酶更能抑制NO。过氧化氢酶作用。这一发现可能解释了在NO存在的情况下，空气中cGMP生成率下降更明显的原因。血红蛋白与NO的比较。过氧化氢酶。这些结果表明，鸟苷环化酶对形成NO的激活剂的反应既取决于内源性血红素受体对NO的刺激活性，也取决于存在的未连接血红素蛋白的相对抑制作用。
The role of NO . catalase in the activation of partially purified soluble guanylate cyclase of rat liver by NaN3 and NH2OH was examined by electron spin resonance (ESR) spectroscopy. Equilibration of bovine liver catalase with NO resulted in formation of a paramagnetic species exhibiting a three-line ESR spectrum similar to that of NO . catalase. This paramagnetic complex produced concentration-dependent stimulation of preparations of partially purified guanylate cyclase that were devoid of detectable endogenous heme content. The stimulation of partially purified guanylate cyclase by NO . catalase was similar to that obtained with NO . hemoglobin and with NO . cytochrome P-420 prepared by reaction of hepatic microsomes of phenobarbital-treated rats with NO. By contrast, these same enzyme preparations did not respond to NO or catalase alone. Addition of hematin or hemoglobin plus a reducing agent to purified guanylate cyclase restored enzyme responsiveness to NO and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), but not to NaN3 or NH2OH. Responses to the latter agents were restored by catalase and potentiated by a H2O2-generating system. Formation of the NO . catalase complex was evident by ESR spectroscopy in test solutions containing NaN3 or nh2oh, catalase, and a glucose-glucose oxidase, H2O2-generating system. The presence of NO . catalase correlated well with the ability of test solutions to activate purified guanylate cyclase. These results provide evidence for catalase-dependent NO generation from NaN3 and NH2OH under conditions leading to guanylate cyclase activation. Preformed NO . hemoglobin or NO . cytochrome P-420 also activated heme-deficient partially purified guanylate cyclase. The ability of several preformed NO . heme protein complexes, but not NO, to stimulate heme-deficient guanylate cyclase supports the concept that formation of the paramagnetic nitrosyl . heme complex, mediated by either enzymatic or nonenzymatic reactions, is a common and essential step in the process by which NO or NO-forming compounds activate guanylate cyclase. In the absence of the NO ligand, both hemoglobin and catalase suppress the stimulatory effects of the corresponding NO . heme proteins on guanylate cyclase. Release of each heme protein from the NO . heme protein complex occurs more rapidly under aerobic compared to anaerobic conditions. However, hemoglobin is approximately 2000 times more effective as an inhibitor of NO . hemoglobin stimulation of guanylate cyclase than is catalase as an inhibitor of NO . catalase action. This finding may explain the more pronounced decline in the rate of cGMP generation in air in the presence of NO . hemoglobin compared to NO . catalase. The results imply that guanylate cyclase responses to activators that can form NO are determined by both the stimulatory activity of the endogenous heme acceptors of NO and the relative inhibitory effects of the unliganded heme proteins present.