Escherichia coli RNR is an a2b2 complex that catalyzes the conversion of nucleotides to deoxynucleotides and requires a diferric-tyrosyl radical (Y�) cofactor to initiate catalysis.   The initiation requires long range PCET over a 35 � between the two subunits by a specific pathway (Y122 D W48 D Y356 within b to Y731 D Y730 D C439 within a).  The rate-limiting step in nucleotide reduction is conformational gating of the PCET process.  Fluorinated tyrosines (FnY where n = 2 or 3) have been incorporated site-specifically in place of Y122. All proteins are able to catalyze multiple turnovers of CDP to dCDP.  RFQ EPR and PELDOR experiments have been carried out with FnY122-b2 and FnY122Y356F-b2.  The results will be discussed in terms of the relative redox potentials of Y356 and Y122 and the potential involvement of W48 in the PCET process.

Site-specific incorporation of F<sub>n</sub>Y (n = 2, 3) in place of Y<sub>122</sub> to probe PCET in class Ia E. coli ribonucleotide reductases

243rd National Meeting (2012)

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Site-specific incorporation of FnY (n = 2, 3) in place of Y122 to probe PCET in class Ia E. coli ribonucleotide reductases

Site-specific incorporation of F_nY (n = 2, 3) in place of Y₁₂₂ to probe PCET in class Ia E. coli ribonucleotide reductases