Conformational change and activation of cytochrome P450 2B1 induced by salt and phospholipid.

Yun CH, Ahn T, Guengerich FP
Arch Biochem Biophys. 1998 356 (2): 229-38

PMID: 9705213 · DOI:10.1006/abbi.1998.0759

A stimulatory effect of increased salt concentration on the enzymatic activity of rat liver microsomes and a reconstituted system containing cytochrome P450 (P450) 2B1 and NADPH-P450 reductase was seen. Structural change of P450 2B1 accompanying the salt-induced increase in its enzyme activity was investigated by circular dichroism, fluorescence spectroscopy, and absorption spectroscopy. It was found that the salt increased alpha-helix content of P450 2B1 in the presence as well as in the absence of a phospholipid. Intrinsic fluorescence emissions also increased with increasing salt concentration. The low-spin iron configuration of P450 2B1 shifted toward the high-spin configuration in response to the increased salt concentration. It was found that the activity increase of P450 coincides with the raised alpha-helix content. The presence of phospholipid magnified this effect. It is proposed that the interaction with salts and phospholipid molecules surrounding P450 2B1 in the endoplasmic reticulum is important for a functional conformation of P450 2B1 in a monooxygenase system including NADPH-P450 reductase.

Copyright 1998 Academic Press.

MeSH Terms (13)

Animals Catalysis Circular Dichroism Cytochrome P-450 CYP2B1 Enzyme Activation Microsomes, Liver Phosphatidylcholines Phospholipids Protein Conformation Rats Sodium Chloride Spectrometry, Fluorescence Structure-Activity Relationship

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