Electrostatic interactions between cytochrome P-450 LM2 and NADPH-cytochrome P-450 reductase.
Electrostatic interactions between cytochrome P-450 LM2 and NADPH-cytochrome P-450 reductase.
复制标题
细胞色素 P-450 LM2 和 NADPH-细胞色素 P-450 还原酶之间的静电相互作用。
DOI：
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发表时间：
1988
期刊：
影响因子：
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通讯作者：
K. Ruckpaul
中科院分区：
文献类型：
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作者：
R. Bernhardt;R. Kraft;A. Otto;K. Ruckpaul
在pH 8.2和100倍摩尔过量的氨基特异性标记2-甲氧基-5-硝基托品酮（MNT）超过蛋白质2 mol MNT/mol P-450 LM 2结合，这导致了50%的整体活性下降，由于从还原酶到血红素蛋白的电子转移速率降低。然而，与产生相同效果的FITC修饰不同，标记物不选择性地结合α-氨基和赖氨酸384，而是与位置49、100、139、144、251、384和433的赖氨酸反应。因此，总活性和还原速率的降低与赖氨酸139、144、251和384的修饰的相对增加相关。因此，除了赖氨酸384之外，赖氨酸139、144和251的ε-氨基是参与与还原酶相互作用的进一步候选者。这一发现支持了我们的P-450和还原酶之间的电荷对接触模型，其中P-450 LM 2的氨基与还原酶的羧基形成盐桥。还原酶支持的P-450还原速度在高盐浓度（I大于222 mM）的微粒体中的减少表明P-450/还原酶相互作用的主导静电特性。基于这些结果和文献数据，提出了P-450 LM 2的膜形貌模型。扩展的电荷对相互作用模型的相互作用机制的其他P-450同工酶和形式与各自的电子供体进行了讨论。
At pH 8.2 and a 100-fold molar excess of the amino group specific label 2-methoxy-5-nitrotropone (MNT) over protein 2 mol MNT/mol P-450 LM2 were bound, which caused a 50% decrease in the overall activity due to a decreased electron transfer rate from reductase to the hemoprotein. However, different from FITC modification, which produces the same effects, the label is not selectively bound to the alpha-amino group and to lysine 384, but reacts with lysines in positions 49, 100, 139, 144, 251, 384 and 433. The decrease in the overall activity and reduction rate thereby correlates with a relative increase in the modification of lysines 139, 144, 251 and 384. Thus, besides lysine 384 the epsilon-amino groups of lysines 139, 144 and 251 are further candidates for participation in the interaction with reductase. This finding supports our model of charge-pair contacts between P-450 and reductase, where amino groups of P-450 LM2 form salt bridges to carboxylic groups of reductase. The decrease of reductase supported P-450 reduction velocity in microsomes at high salt concentration (I greater than 222 mM) indicates the dominant electrostatic character of P-450/reductase interaction. Based on these results and data from the literature a model of membrane topography of P-450 LM2 has been proposed. Extension of the charge pair interaction model to interaction mechanisms of other P-450 isoenzymes and forms with their respective electron donors is discussed.