Deciphering Radical Transport in the Large Subunit of Class I Ribonucleotide Reductase
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CitationHolder, Patrick G., Arturo A. Pizano, Bryce L. Anderson, JoAnne Stubbe, and Daniel G. Nocera. 2012. “Deciphering Radical Transport in the Large Subunit of Class I Ribonucleotide Reductase.” Journal of the American Chemical Society 134 (2) (January 18): 1172–1180. doi:10.1021/ja209016j.
AbstractIncorporation of 2,3,6-trifluorotyrosine (F3Y) and a rhenium bipyridine ([Re]) photooxidant into a peptide corresponding to the C-terminus of the β protein (βC19) of Escherichia coli ribonucleotide reductase (RNR) allows for the temporal monitoring of radical transport into the α2 subunit of RNR. Injection of the photogenerated F3Y radical from the [Re]–F3Y–βC19 peptide into the surface accessible Y731 of the α2 subunit is only possible when the second Y730 is present. With the Y–Y established, radical transport occurs with a rate constant of 3 × 105 s−1. Point mutations that disrupt the Y–Y dyad shut down radical transport. The ability to obviate radical transport by disrupting the hydrogen bonding network of the amino acids composing the co-linear proton-coupled electron transfer pathway in α2 suggests a finely tuned evolutionary adaptation of RNR to control the transport of radicals in this enzyme.
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