Reduction kinetics of purified rat liver cytochrome P-450. Evidence for a sequential reaction mechanism dependent on the hemoprotein spin state.
Reduction kinetics of purified rat liver cytochrome P-450. Evidence for a sequential reaction mechanism dependent on the hemoprotein spin state.
复制标题
纯化的大鼠肝细胞色素 P-450 的还原动力学。
DOI：
10.1021/bi00315a004
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发表时间：
1984
期刊：
影响因子：
2.9
通讯作者：
Schenkman,JB
中科院分区：
文献类型：
--
作者：
Tamburini,PP;Gibson,GG;Backes,WL;Sligar,SG;Schenkman,JB
Paul P. Tamburini、G. Gordon Gibson、* Wayne L. Backes、Stephen G. Sligar 和 John B. Schenkman 摘要：对来自苯巴比妥处理的大鼠肝微粒体的纯化大鼠肝铁细胞色素 P-450 的厌氧还原动力学进行了研究，并用饱和 NADPH-细胞色素 P-450 还原酶重构，结果表明，单相。通过将快相还原速率的变化与平衡前存在的血红素铁的自旋态相关联的实验，获得了与细胞色素P-450还原的自旋态控制模型一致的数据，其中血红素蛋白的高自旋形式比低自旋形式还原得更快。此外，肝微粒体细胞色素 P-450 催化序列的早期步骤之一是 NADPH-细胞色素 P-450 还原酶对血红素蛋白进行单电子还原（Peterson 等，1977）。该过程通常在饱和浓度一氧化碳存在的非稳态条件下进行厌氧研究。由此产生的动力学并不表现出简单的一级行为，并促使人们对控制这一过程的分子机制的性质进行了许多研究。动力学先前已被分解为两个（Gigon 等人，1969；Oprian 等人，1979；Peterson 等人，1976、1978；Taniguchi 等人，1979）或更多（Ruf，1980）相，这些相被描述为两个一级过程或多个一级过程的复合体。
Paul P. Tamburini, G. Gordon Gibson,* Wayne L. Backes, Stephen G. Sligar, and John B. Schenkman abstract: The anaerobic reduction kinetics of purified rat liver ferric cytochrome P-450 from phenobarbital-treated rat liver microsomes, reconstituted with saturating NADPH-cy-tochrome P-450 reductase, have been investigated and were shown not to be monophasic. From experimentscorrelating changes in the rate of fast-phase reduction with the spin state of the heme iron existing at preequilibrium, data were obtained consistent with a model for spin-state control of cytochrome P-450 reduction wherein the high-spin form of the hemoprotein is more rapidly reduced than the low-spin form. In addition, One of the early steps in the catalytic sequence of hepatic microsomal cytochrome P-450 is a one-electron reduction of the hemoprotein by NADPH-cytochrome P-450 reductase (Peterson et al., 1977). This process has generally been studied anaerobically under non-steady-state conditions in the presence of saturating concentrations of carbon monoxide. The resultant kinetics do not show simple first-order behavior and have prompted many investigations into the nature of the molecular mechanisms governing this process. The kinetics have pre-viously been resolved into either two (Gigon et al., 1969; Oprian et al., 1979; Peterson et al., 1976, 1978; Taniguchi et al., 1979) or more (Ruf, 1980) phases, which have been described as a composite of two first-order processes or a more