Electron-Tunneling Pathways in Cytochrome c
Abstract
Distant Fe2+-Ru3+ electronic couplings have been extracted from intramolecular electron-transfer rates in Ru(histidine^x) (where X = 33, 39, 62, and 72) derivatives of cytochrome c. The couplings increase according to 62 (0.0060) < 72 (0.057) < 33 (0.097) < 39 (0.11 per wave numbers); however, this order is out of line with the histidine to heme edge-edge distances [62 (14.8) > 39 (12.3) > 33 (11.1) > 72 (8.4 angstroms)]. The rates (and the couplings) correlate with the lengths of σ-tunneling pathways comprised of covalent bonds, hydrogen bonds, and through-space jumps from the histidines to the heme group. Space jumps greatly decrease couplings: One from Pro71 to Met80 extends the σ-tunneling length of the His^72 pathway by roughly 10 covalent-bond units.
Additional Information
© 1992 American Association for the Advancement of Science. 27 December 1991; accepted 10 March 1992. We thank D. N. Beratan for assistance with the pathway analyses and for many helpful discussions. D.S.W. acknowledges an NSF predoctoral fellowship and a fellowship from the Parsons Foundation. M.J.B. was the Carlsberg Foundation Scholar in the Beckman Institute during 1990-91. Supported by National Science Foundation grants CHE-8822988 and CHE-9119992.Additional details
- Eprint ID
- 53928
- Resolver ID
- CaltechAUTHORS:20150121-092819858
- NSF Predoctoral Fellowship
- Ralph M. Parsons Foundation
- Carlsberg Foundation
- CHE-8822988
- NSF
- CHE-9119992
- NSF
- Created
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2015-01-21Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field