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标题：Insights into the Role of Substrates on the Interaction between Cytochrome b5 and Cytochrome P450 2B4 by NMR
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作者：Meng Zhang ; Stéphanie V. Le Clair ; Rui Huang 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2015
卷号：5
期号：1
DOI：10.1038/srep08392
语种：English
出版社：Springer Nature
摘要：Mammalian cytochrome b ₅ (cyt b ₅) is a membrane-bound protein capable of donating an electron to cytochrome P450 (P450) in the P450 catalytic cycle. The interaction between cyt b ₅ and P450 has been reported to be affected by the substrates of P450; however, the mechanism of substrate modulation on the cyt b ₅-P450 complex formation is still unknown. In this study, the complexes between full-length rabbit cyt b ₅ and full-length substrate-free/substrate-bound cytochrome P450 2B4 (CYP2B4) are investigated using NMR techniques. Our findings reveal that the population of complexes is ionic strength dependent, implying the importance of electrostatic interactions in the complex formation process. The observation that the cyt b ₅-substrate-bound CYP2B4 complex shows a weaker dependence on ionic strength than the cyt b ₅-substrate-free CYP2B4 complex suggests the presence of a larger fraction of steoreospecific complexes when CYP2B4 is substrate-bound. These results suggest that a CYP2B4 substrate likely promotes specific interactions between cyt b ₅ and CYP2B4. Residues D65, V66, T70, D71 and A72 are found to be involved in specific interactions between the two proteins due to their weak response to ionic strength change. These findings provide insights into the mechanism underlying substrate modulation on the cyt b ₅-P450 complexation process.