Abstract
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 s o) and heme-cysteine distances for 62, 383, and 387 are 50 s -1 and 16 Å, 0.8 s - 1 and 25 Å, and 650 s - 1 and 19 Å. 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 s o values correlating with more electrons transferred per dioxygen during catalysis.
Original language | English (US) |
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Pages (from-to) | 1350-1353 |
Number of pages | 4 |
Journal | Journal of Inorganic Biochemistry |
Volume | 105 |
Issue number | 10 |
DOIs | |
State | Published - Oct 2011 |
Funding
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.
Keywords
- Biocatalysis
- Cytochrome P450
- Dioxygen reduction
- Electrochemistry
- Electron transfer
ASJC Scopus subject areas
- Biochemistry
- Inorganic Chemistry