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Spectroscopy and Electrochemistry of Cytochrome P450 BM3-Surfactant Film Assemblies

Udit, Andrew K. and Hagen, Katharine D. and Goldman, Peter J. and Star, Andrew and Gillan, James M. and Gray, Harry B. and Hill, Michael G. (2006) Spectroscopy and Electrochemistry of Cytochrome P450 BM3-Surfactant Film Assemblies. Journal of the American Chemical Society, 128 (31). pp. 10320-10325. ISSN 0002-7863. https://resolver.caltech.edu/CaltechAUTHORS:20170512-144736551

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Abstract

We report analyses of electrochemical and spectroscopic measurements on cytochrome P450 BM3 (BM3) in didodecyldimethylammonium bromide (DDAB) surfactant films. Electronic absorption spectra of BM3−DDAB films on silica slides reveal the characteristic low-spin Fe^(III) heme absorption maximum at 418 nm. A prominent peak in the absorption spectrum of BM3 Fe^(II)−CO in a DDAB dispersion is at 448 nm; in spectra of aged samples, a shoulder at ∼420 nm is present. Infrared absorption spectra of the BM3 Fe^(II)−CO complex in DDAB dispersions feature a time-dependent shift of the carbonyl stretching frequency from 1950 to 2080 cm^(-1). Voltammetry of BM3-DDAB films on graphite electrodes gave the following results: Fe^(III/II) E_(1/2) at −260 mV (vs SCE), ∼300 mV positive of the value measured in solution; ΔS°_(rc), ΔS°, and ΔH° values for water-ligated BM3 in DDAB are −98 J mol^(-1) K^(-1), −163 J mol^(-1) K^(-1), and −47 kJ mol^(-1), respectively; values for the imidazole-ligated enzyme are −8 J mol^(-1) K^(-1), −73 J mol^(-1) K^(-1), and −21 kJ mol^(-1). Taken together, the data suggest that BM3 adopts a compact conformation within DDAB that in turn strengthens hydrogen bonding interactions with the heme axial cysteine, producing a P420-like species with decreased electron density around the metal center.


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http://dx.doi.org/10.1021/ja061896wDOIArticle
http://pubs.acs.org/doi/abs/10.1021/ja061896wPublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/ja061896wRelated ItemSupporting Information
Additional Information:© 2006 American Chemical Society. Received 20 March 2006. Published online 18 July 2006. Published in print 1 August 2006. We thank C. E. Immoos, P. J. Farmer, and L. A. Waskell for helpful discussions. Supported by HHMI (A.K.U.), the Camile and Henry Dreyfus Foundation (M.G.H.), NIH (DK19038 to H.B.G.), and the Ellison Medical Foundation (Senior Scholar Award in Aging to H.B.G.).
Funders:
Funding AgencyGrant Number
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Camile and Henry Dreyfus FoundationUNSPECIFIED
NIHDK19038
Ellison Medical FoundationUNSPECIFIED
Issue or Number:31
Record Number:CaltechAUTHORS:20170512-144736551
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170512-144736551
Official Citation:Spectroscopy and Electrochemistry of Cytochrome P450 BM3-Surfactant Film Assemblies Andrew K. Udit, Katharine D. Hagen, Peter J. Goldman, Andrew Star, James M. Gillan, Harry B. Gray, and Michael G. Hill Journal of the American Chemical Society 2006 128 (31), 10320-10325 DOI: 10.1021/ja061896w
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77431
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:12 May 2017 22:55
Last Modified:03 Oct 2019 17:57

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