Electron transfer and catalytic control by the iron-sulfur clusters in a respiratory enzyme, E. coli fumarate reductase JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Hudson, J. M., Heffron, K., Kotlyar, V., Sher, Y., Maklashina, E., Cecchini, G., Armstrong, F. A. 2005; 127 (19): 6977-6989

Abstract

Factors governing the efficacy of long-range electron relays in enzymes have been examined using protein film voltammetry in conjunction with site-directed mutagenesis. Investigations of the fumarate reductase from Escherichia coli, in which three Fe-S clusters relay electrons over more than 30 A, lead to the conclusion that varying the medial [4Fe-4S] cluster potential over a 100 mV range does not have a significant effect on the inherent kinetics of electron transfer to and from the active-site flavin. The results support a proposal that the reduction potential of an individual electron relay site in a multicentered enzyme is not a strong determinant of activity; instead, as deduced from the potential dependence of catalytic electron transfer, electron flow through the intramolecular relay is rapid and reversible, and even uphill steps do not limit the catalytic rate.

View details for DOI 10.1021/ja043404q

View details for Web of Science ID 000229085200032

View details for PubMedID 15884941