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Electron tunneling in protein crystals

Tezcan, F. Akif and Crane, Brian R. and Winkler, Jay R. and Gray, Harry B. (2001) Electron tunneling in protein crystals. Proceedings of the National Academy of Sciences of the United States of America, 98 (9). pp. 5002-5006. ISSN 0027-8424. PMCID PMC33153. doi:10.1073/pnas.081072898.

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The current understanding of electron tunneling through proteins has come from work on systems where donors and accepters are held at fixed distances and orientations. The factors that control electron flow between proteins are less well understood, owing to uncertainties in the relative orientations and structures of the reactants during the very short time that tunneling occurs. As we report here, the way around such structural ambiguity is to examine oxidation-reduction reactions in protein crystals. Accordingly, we have measured and analyzed the kinetics of electron transfer between native and Zn-substituted tuna cytochrome c (cyt c) molecules in crystals of known structure. Electron transfer rates [(320 s(-1) for *Zn-cyt c --> Fe(III)-cyt c; 2000 s(-1) for Fe(II)-cyt c --> Zn-cyt c(+))] over a Zn-Fe distance of 24.1 Angstrom closely match those for intraprotein electron tunneling over similar donor-acceptor separations. Our results indicate that van der Waals interactions and water-mediated hydrogen bonds are effective coupling elements for tunneling across a protein-protein interface.

Item Type:Article
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URLURL TypeDescription CentralArticle
Tezcan, F. Akif0000-0002-4733-6500
Winkler, Jay R.0000-0002-4453-9716
Gray, Harry B.0000-0002-7937-7876
Additional Information:© 2001 by the National Academy of Sciences. Contributed by Harry B. Gray, February 13, 2001. We thank D. C. Rees and the Stanford Synchrotron Research Laboratory for access to data collection facilities, and A. M. Bilwes for technical assistance and helpful discussions. B.R.C. acknowledges the Helen Hay Whitney Foundation for a postdoctoral fellowship. This work was supported by the National Science Foundation and the Arnold and Mabel Beckman Foundation. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Funding AgencyGrant Number
Helen Hay Whitney FoundationUNSPECIFIED
Arnold and Mabel Beckman FoundationUNSPECIFIED
Issue or Number:9
PubMed Central ID:PMC33153
Record Number:CaltechAUTHORS:TEZpnas01
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:940
Deposited By: Tony Diaz
Deposited On:15 Nov 2005
Last Modified:08 Nov 2021 19:06

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