Electron transfer and catalytic control by the iron-sulfur clusters in a respiratory enzyme, E. coli fumarate reductase.

Journal article

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.

Authors: Hudson, J; Heffron, K; Kotlyar, V; Sher, Y; Maklashina, E

• Publication status: Published
• Journal: Journal of the American Chemical Society
• Volume: 127
• Issue: 19
• Pages: 6977-6989
• Publication date: 2005-05-01
• DOI: 10.1021/ja043404q
• EISSN: 1520-5126
• ISSN: 0002-7863
• Language: English
• Keywords: Flavins; Structure-Activity Relationship; Oxidation-Reduction; Mutation, Missense; Sequence Alignment; Iron-Sulfur Proteins; Kinetics; Mutagenesis, Site-Directed; Electrochemistry; Succinate Dehydrogenase; Catalysis; Escherichia coli; Amino Acid Sequence; Models, Molecular