NDLI: Structure, electronic properties and catalytic behaviour of an activity-enhancing CYP102A1 $(P450

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Yang, Wen Bartlam, Mark Wong, Luet-lok Rao, Zihe Whitehouse, Christopher J. C. Tufton, Henry G. Bell, Stephen G. Yorke, Jake A. Ogilvie, Lydia C. I. Zhou, Weihong
Description	Author Affiliation: Whitehouse CJ ( Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, UK.)
Abstract	The substrate-free crystal structure of a five-mutation directed evolution variant of CYP102A1 $(P450_{BM3})$ with generic activity-enhancing properties (“KT2”) has been determined to 1.9-Å resolution. There is a close resemblance to substrate-bound structures of the wild-type enzyme (WT). The disruption of two salt bridges that link the G- and I-helices in WT causes conformational changes that break several hydrogen bonds and reduce the angle of the kink in the I-helix where dioxygen activation is thought to take place. The side-chain of a key active site residue, Phe87, is rotated in one molecule of the asymmetric unit, and the side-chains of Phe158 and Phe261 cascade into the orientations found in fatty-acid-bound forms of the enzyme. The iron is out of the porphyrin plane, towards the proximal cysteine. Unusually, the axial water ligand to the haem iron is not hydrogen-bonded to Ala264. The first electron transfer from the reductase domain to the haem domain of substrate-free KT2 is almost as fast as in palmitate-bound WT even though the reduction potential of the haem domain is only slightly more oxidising than that of substrate-free WT. However, NADPH is turned over slowly in the absence of substrate, so the catalytic cycle is gated by a step subsequent to the first electron transfer—a contrast to WT. Propylbenzene binding slightly raises the first electron transfer rate in WT but not in KT2. It is proposed that the generic rate accelerating properties of KT2 arise from the substrate-free form being in a catalytically ready conformation, such that substrate-induced changes to the structure play a less significant role in promoting the first electron transfer than in WT.
ISSN	14779226
Issue Number	40
Volume Number	40
e-ISSN	13645447
Journal	Dalton Trans.
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2011-10-28
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Bacterial Proteins Chemistry Cytochrome P-450 Enzyme System NADPH-Ferrihemoprotein Reductase Genetics Metabolism Benzene Derivatives Catalysis Crystallography, X-Ray Electron Transport Electrons Hydrogen Bonding Kinetics Mutation Oxidation-Reduction Protein Structure, Tertiary Journal Article Research Support, Non-U.S. Gov't
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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