title: Deciphering radical transport in the large subunit of class I ribonucleotide reductase.
abstract: Incorporation of 2,3,6-trifluorotyrosine (F(3)Y) 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 F(3)Y radical from the [Re]-F(3)Y-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 × 10(5) 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 colinear proton-coupled electron transfer pathway in α2 suggests a finely tuned evolutionary adaptation of RNR to control the transport of radicals in this enzyme.
authors: Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
authors: Patrick G
authors: PG
authors: Holder
authors: Arturo A
authors: AA
authors: Pizano
authors: Bryce L
authors: BL
authors: Anderson
authors: Joanne
authors: J
authors: Stubbe
authors: Daniel G
authors: DG
authors: Nocera
mesh_terms: D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D005095:Exoribonucleases / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D029968:Escherichia coli Proteins; C489683:rnr protein, E coli; D005095:Exoribonucleases