特异性和非特异性的影响钾离子在细胞色素substrate-protein交互P450cam P450lin。
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吉尔Deprez E, E,赫尔姆斯V,韦德RC回族好,阿花G
特异性和非特异性的影响钾离子在细胞色素substrate-protein交互P450cam P450lin。
J Inorg。2002年9月20,91 (4):597 - 606。
- PubMed ID
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12237225 (在PubMed]
- 文摘
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底物结合细胞色素P450cam通常被认为是一个两步的过程。第一步对应于衬底的入口,樟脑,血红素的口袋里。第二步对应于一个自旋过渡(低自旋- - >高自旋)的铁protein-substrate复杂。这个自旋过渡与活性部位内的底物的流动(Biochim Biophys学报1338 (1997)77)。阳离子钾(K(+))有一个特定的旋转平衡。这通常归因于K(+)离子感应构象改变96年酪氨酸的羟基氢连着樟脑酮组和结果最佳衬底取向和减少流动性的底物的活性部位。在本文中,我们表明,K(+)不仅影响substrate-Tyr 96几,但行为更多全球自K(+)影响也观察到在Tyr96Phe突变以及与camphor-analogues复合物。大的化合物,血红素口袋,适合的结合亲和力高于樟脑,显示高自旋的内容较少依赖K(+)的存在。相比之下,K(+)有重大影响的高自旋内容substrate-cytochrome P450cam复合物与宽松的交互。我们认为大化合物亲和力高于樟脑范德华接触更多的活性位点残基。 Their mobilities are then reduced and less dependent on the presence of K(+). In this study, we also explored, for comparison, the K(+) effect on the spin transition state of another member of the P450 superfamily, cytochrome P450lin. This effect is not as strong as those observed for cytochrome P450cam. Even though the spin equilibrium does not change dramatically in the presence of K(+) or Na(+), the value of the dissociation constant (K(d)) for linalool binding is significantly affected by ionic strength. Analysis of the thermodynamic parameters for the linalool binding strongly suggests that, similarly to our previous finding for cytochrome P450cam, electrostatic gates participate in the control of substrate access.