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Substrate analogue induced changes of the CO-stretching mode in cytochrome P-450cam carbon monoxide complex

Item Type:Article
Title:Substrate analogue induced changes of the CO-stretching mode in cytochrome P-450cam carbon monoxide complex
Creators Name:Jung, C. and Hoa, G.H.B. and Schroeder, K.L. and Simon, M. and Doucet, J.P.
Abstract: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.
Keywords:Camphor, Camphor 5-Monooxygenase, Carbon Monoxide, Cytochrome P-450 Enzyme System, Fourier Analysis, Hydrogen Bonding, Infrared Spectrophotometry, Mixed Function Oxygenases
Source:Biochemistry
ISSN:0006-2960
Publisher:American Chemical Society (U.S.A.)
Volume:31
Number:51
Page Range:12855-12862
Date:29 December 1992
Official Publication:https://doi.org/10.1021/bi00166a021
PubMed:View item in PubMed

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