van der Felt, Clairisse and Hindoyan, Kevork and Choi, Kang and Javdan, Nazafarin and Goldman, Peter and Bustos, Rose and Star, Andrew G. and Hunter, Bryan M. and Hill, Michael G. and Nersissian, Aram and Udit, Andrew K. (2011) Electron-transfer rates govern product distribution in electrochemically-driven P450-catalyzed dioxygen reduction. Journal of Inorganic Biochemistry, 105 (10). pp. 1350-1353. ISSN 0162-0134 http://resolver.caltech.edu/CaltechAUTHORS:20111108-085005468
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Developing electrode-driven biocatalytic systems utilizing the P450 cytochromes for selective oxidations depends not only on achieving electron transfer (ET) but also doing so at rates that favor native-like turnover. Herein we report studies that correlate rates of heme reduction with ET pathways and resulting product distributions. We utilized single-surface cysteine mutants of the heme domain of P450 from Bacillus megaterium and modified the thiols with N-(1-pyrene)-iodoacetamide, affording proteins that could bond to basal-plane graphite. Of the proteins examined, Cys mutants at position 62, 383, and 387 were able to form electroactive monolayers with similar E_(1/2) values (− 335 to − 340 mV vs AgCl/Ag). Respective ET rates (k_so) and heme-cysteine distances for 62, 383, and 387 are 50 s^(-1) and 16 Ǻ, 0.8 s^(–1) and 25 Ǻ, and 650 s^(–1) and 19 Ǻ. Experiments utilizing rotated-disk electrodes were conducted to determine the products of P450-catalyzed dioxygen reduction. We found good agreement between ET rates and product distributions for the various mutants, with larger k_so values correlating with more electrons transferred per dioxygen during catalysis.
|Additional Information:||© 2011 Elsevier Inc. Received 15 November 2010. Received in revised form 1 February 2011. Accepted 9 March 2011. Available online 22 March 2011. We are grateful to Dr. Lionel Cheruzel for providing mutants 97 and 397, and to Professor Harry Gray for the helpful discussions. Acknowledgement is made to the Donors of the American Chemical Society Petroleum Research Fund (AKU and MGH) and the Dreyfus Foundation (AKU) for support of this research. We additionally acknowledge the Howard Hughes Medical Institute for financial support (undergraduate education grant) and The Beckman Foundation to acknowledge financial support to BMH.|
|Subject Keywords:||Cytochrome P450; Electrochemistry; Biocatalysis; Electron transfer; Dioxygen reduction|
|Official Citation:||Clairisse van der Felt, Kevork Hindoyan, Kang Choi, Nazafarin Javdan, Peter Goldman, Rose Bustos, Andrew G. Star, Bryan M. Hunter, Michael G. Hill, Aram Nersissian, Andrew K. Udit, Electron-transfer rates govern product distribution in electrochemically-driven P450-catalyzed dioxygen reduction, Journal of Inorganic Biochemistry, Volume 105, Issue 10, October 2011, Pages 1350-1353, ISSN 0162-0134, 10.1016/j.jinorgbio.2011.03.006. (http://www.sciencedirect.com/science/article/pii/S016201341100047X)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||08 Nov 2011 17:08|
|Last Modified:||08 Nov 2011 17:08|
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