Function of the diiron cluster of Escherichia coli class Ia ribonucleotide reductase in proton-coupled electron transfer.

ABSTRACT: The class Ia ribonucleotide reductase (RNR) from Escherichia coli employs a free-radical mechanism, which involves bidirectional translocation of a radical equivalent or "hole" over a distance of ~35 Å from the stable diferric/tyrosyl-radical (Y122(•)) cofactor in the β subunit to cysteine 439 (C439) in the active site of the α subunit. This long-range, intersubunit electron transfer occurs by a multistep "hopping" mechanism via formation of transient amino acid radicals along a specific pathway and is thought to be conformationally gated and coupled to local proton transfers. Whereas constituent amino acids of the hopping pathway have been identified, details of the proton-transfer steps and conformational gating within the β sununit have remained obscure; specific proton couples have bee

SUBMITTER: Worsdorfer B 

PROVIDER: S-EPMC3869997 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature