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Oxoiron(IV) in Chloroperoxidase Compound II Is Basic: Implications for P450 Chemistry

Green, Michael T. and Dawson, John H. and Gray, Harry B. (2004) Oxoiron(IV) in Chloroperoxidase Compound II Is Basic: Implications for P450 Chemistry. Science, 304 (5677). pp. 1653-1656. ISSN 0036-8075. doi:10.1126/science.1096897. https://resolver.caltech.edu/CaltechAUTHORS:20141114-143753781

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Abstract

With the use of x-ray absorption spectroscopy, we have found that the Fe-O bond in chloroperoxidase compound II (CPO-II) is much longer than expected for an oxoiron(IV) (ferryl) unit; notably, the experimentally determined bond length of 1.82(1) Å accords closely with density functional calculations on a protonated ferryl (Fe^(IV)-OH, 1.81 Å). The basicity of the CPO-II ferryl [pK_a > 8.2 (where K_a is the acid dissociation constant)] is attributable to strong electron donation by the axial thiolate. We suggest that the CPO-II protonated ferryl is a good model for the rebound intermediate in the P450 oxygenation cycle; with elevated pK_a values after one-electron reduction, thiolate-ligated ferryl radicals are competent to oxygenate saturated hydrocarbons at potentials that can be tolerated by folded polypeptide hosts.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1126/science.1096897DOIArticle
http://www.sciencemag.org/content/304/5677/1653PublisherArticle
ORCID:
AuthorORCID
Gray, Harry B.0000-0002-7937-7876
Additional Information:© 2004 American Association for the Advancement of Science. 18 February 2004; Accepted 21 April 2004. We thank M. Bollinger, I. Dmochowski, J. Labinger, M. Machczynski, M. McGuirl, A. Tezcan, and J. Winkler for helpful discussions; G. George, I. Pickering, M. Latimer, B. Butler, A. Soo Hoo, S. Debeer George, D. Durkin, and other SSRL staff members for assistance with XAS measurements; and L. Hager for a CPO sample used in the initial experiments. Supported by NIH (GM26730 to J.H.D. and DK19038 to H.B.G.), NSF, and the Arnold and Mabel Beckman Foundation.
Funders:
Funding AgencyGrant Number
NIHGM26730
NIHDK19038
NSFUNSPECIFIED
Arnold and Mabel Beckman FoundationUNSPECIFIED
Issue or Number:5677
DOI:10.1126/science.1096897
Record Number:CaltechAUTHORS:20141114-143753781
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20141114-143753781
Official Citation:Green, M. T., Dawson, J. H., & Gray, H. B. (2004). Oxoiron(IV) in Chloroperoxidase Compound II Is Basic: Implications for P450 Chemistry. Science, 304(5677), 1653-1656. doi: 10.1126/science.1096897
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51798
Collection:CaltechAUTHORS
Deposited By: Joanne McCole
Deposited On:15 Nov 2014 00:55
Last Modified:10 Nov 2021 19:15

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