Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published May 15, 1992 | public
Journal Article

Electron-Tunneling Pathways in Cytochrome c


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

August 20, 2023
October 19, 2023