Proton-coupled electron hopping in Ru-modified P. aeruginosa azurin

• DOI: 10.1007/s00775-016-1332-4
• Publication Date: 2016-01-20T14:59:22Z
• Authors: Jeffrey J. Warren; Oliver S. Shafaat; Jay R. Winkler; Harry B. Gray
• Keywords: Azurin; Imidazole; Proton-Coupled Electron Transfer

We constructed two artificial multiple-step electron transfer (hopping) systems based on Pseudomonas aeruginosa azurin where a tyrosine (YOH) is situated between Ru(2,2'-bipyridine)2(imidazole)(histidine) and the native copper site: RuH107YOH109 and RuH124-YOH122. We investigated the rates of Cu(I) oxidation by flash-quench generated Ru(III) over a range of conditions that probed the role of proton-coupled oxidation/reduction of YOH in the reaction. Rates of Cu(I) oxidation were enhanced over single-step electron transfer by factors between 3 and 80, depending on specific scaffold and buffer conditions.