Substrate analogue induced changes of the CO-stretching mode in the cytochrome P450cam-carbon monoxide complex.
Substrate analogue induced changes of the CO-stretching mode in the cytochrome P450cam-carbon monoxide complex.
复制标题
底物类似物诱导细胞色素 P450cam-一氧化碳复合物中 CO 拉伸模式的变化。
作者：
C. Jung;G. H. Hoa;K. Schröder;M. Simon;J. Doucet
CO-拉伸模式的一氧化碳配体在还原细胞色素P450凸轮，在不存在或存在的樟脑和9种不同的樟脑类似物的存在下，在室温下使用傅里叶变换红外光谱测定。无底物的细胞色素P450 cam-CO揭示了一个广泛的，略有结构化的频带从几个伸缩模式信号的重叠。众多的信号表明，细胞色素P450存在于几个构象亚态的动态平衡。樟脑或樟脑类似物的结合强烈影响这种平衡。对于不能与酪氨酸96的羟基形成氢键的底物类似物，CO-伸缩带相当宽且不对称。与此相反，底物类似物与一个醌基形成氢键的Tyr 96 OH诱导的CO-伸缩模带的位移和锐化。对于具有两个杂基团的底物类似物，红外光谱略微不对称或出现次要带。空间位阻、底物迁移率和蛋白质柔性最终决定CO-伸缩模式信号的位置和宽度。
The CO-stretching mode of the carbon monoxide ligand in reduced cytochrome P450cam, in the absence or presence of camphor and in the presence of nine different camphor analogues, was measured at room temperature using Fourier transform infrared spectroscopy. Substrate-free cytochrome P450cam--CO reveals a broad, slightly structured band resulting from an overlap of several stretching mode signals. The multitude of the signals indicates that cytochrome P450 exists in a dynamic equilibrium of several conformational substates. Binding of camphor or camphor analogues strongly influences this equilibrium. For substrate analogues which are not able to form a hydrogen bond to the hydroxyl group of tyrosine 96, the CO-stretching band is rather broad and asymmetric. In contrast, substrate analogues with one quinone group which form a hydrogen bond to the Tyr96 OH induce a shift and a sharpening of the CO-stretching mode band. For substrate analogues with two hetero groups, the infrared spectrum is slightly asymmetric or a minor band appears. Sterical hindrance, substrate mobility, and protein flexibility finally determine the position and width of the CO-stretching mode signals.