Usanov S A, Chernogolov A A, Chashchin V L, Akhrem A A
Biokhimiia. 1985 Oct;50(10):1702-11.
The two main approaches presently used for cytochrome P-450scc modelling are as follows: i) the use of chemical compounds carrying activated oxygen species, e. g., peracids, organic hydroperoxides, iodosobenzene, etc., ii) the use of electrochemical reduction in the presence of redox-active compounds. In the present work, a new model system for simulation of steroidogenic electron transfer is proposed, which reduces cytochrome P-450 scc by NADPH in the absence of adrenodoxin reductase and adrenodoxin. Phenazine methosulfate is used as an electron carrier. More than 95% of cytochrome P-450scc is reduced in a model system. The reduction kinetics is characterized by a lag phase, thus indicating complex formation between cytochrome P-450scc and phenazine methosulfate or formation of intermediate reducing equivalents. NADH may also serve as an electron donor for cytochrome P-450scc. Phenazine methosulfate can reduce microsomal cytochrome P-450 LM2 and b5, but not cytochrome P-450 LM4. Superoxide dismutase does not affect the reduction, thus indicating that O9.- is not involved in the reduction process. The mechanism of hemoprotein reduction and the nature of intermediates which can be formed in the model system is proposed.
目前用于细胞色素P - 450scc建模的两种主要方法如下：i）使用携带活性氧的化合物，例如过氧酸、有机氢过氧化物、亚碘酰苯等；ii）在存在氧化还原活性化合物的情况下进行电化学还原。在本研究中，提出了一种用于模拟类固醇生成电子转移的新模型系统，该系统在没有肾上腺皮质铁氧化还原蛋白还原酶和肾上腺皮质铁氧化还原蛋白的情况下，通过NADPH还原细胞色素P - 450scc。硫酸甲酯吩嗪用作电子载体。在模型系统中，超过95%的细胞色素P - 450scc被还原。还原动力学的特征是存在一个延迟期，这表明细胞色素P - 450scc与硫酸甲酯吩嗪之间形成了复合物，或者形成了中间还原当量。NADH也可以作为细胞色素P - 450scc的电子供体。硫酸甲酯吩嗪可以还原微粒体细胞色素P - 450 LM2和b5，但不能还原细胞色素P - 450 LM4。超氧化物歧化酶不影响还原过程，因此表明O₂⁻不参与还原过程。本文提出了血红素蛋白还原的机制以及在模型系统中可能形成的中间体的性质。
