...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Inorganic Biochemistry: An Interdisciplinary Journal >Examining the mechanism of stimulation of cytochrome P450 by cytochrome b(5): the effect of cytochrome b(5) on the interaction between cytochrome P4502B4 and P450 reductase
【24h】

Examining the mechanism of stimulation of cytochrome P450 by cytochrome b(5): the effect of cytochrome b(5) on the interaction between cytochrome P4502B4 and P450 reductase

机译：检查细胞色素b（5）刺激细胞色素P450的机理：细胞色素b（5）对细胞色素P4502B4和P450还原酶之间相互作用的影响

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Dissociation constants K-d for cytochrome P450 reductase (reductase) and cytochrome P450 2134 are measured in the presence of various substrates. Aminopyrine increases the dissociation constant for binding of the two proteins. Furthermore, cytochrome b(5) (b(5)) stimulates metabolism of this substrate and dramatically decreases the substrate-related K, values. Experiments are performed to test if the b(5)-mediated stimulation is effected through a conformational change of P450. The effects of a redox-inactive analogue of b(5) (Mn b(5)) on product formation and reaction stoichiometry are determined. Variations in the concentration of Mn b5 stock solution that have been shown to effect the aggregation state of the protein alter the rate of P450-mediated NADPH oxidation but have no effect on the rate of product formation. Thus, the electron transfer capability of b(5) is necessary for stimulation of metabolism. Furthermore, stopped flow spectrometry measurements of the rate of first electron reduction of the P450 by reductase indicate that the coupling of P450 2B4-mediated metabolism improves, in the presence of Mn b(5), with slower delivery of the first electron of the catalytic cycle by the reductase. These results are consistent with a model involving the regulation of the P450 catalytic cycle by conformational changes of the P450 enzyme. We propose that the conformational change(s) necessary for progression of the catalytic cycle is inhibited when reduced, but not oxidized, reductase is bound to the P450.
机译：在存在各种底物的情况下测量细胞色素P450还原酶（还原酶）和细胞色素P450 2134的解离常数K-d。氨基比林增加了两个蛋白结合的解离常数。此外，细胞色素b（5）（b（5））刺激该底物的新陈代谢并显着降低底物相关的K i值。进行实验以测试b（5）介导的刺激是否通过P450的构象变化实现。确定了b（5）（Mn b（5））的氧化还原无活性类似物对产物形成和反应化学计量的影响。已显示影响蛋白质聚集状态的Mn b5储备溶液浓度变化会改变P450介导的NADPH氧化速率，但对产物形成速率没有影响。因此，b（5）的电子转移能力对于刺激新陈代谢是必需的。此外，停止流动光谱法测量还原酶对P450的第一电子还原的速率表明，在存在Mn b（5）的情况下，P450 2B4介导的新陈代谢的耦合得以改善，而催化性第一电子的传递较慢通过还原酶循环。这些结果与涉及通过P450酶的构象变化调节P450催化循环的模型一致。我们提出当还原而不是氧化的还原酶与P450结合时，抑制了催化循环进行所必需的构象变化。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号