ORGN 228 |
| Cyril S. Yee, Jenny Gie, Michelle C.Y. Chang, Daniel G. Nocera, and JoAnne Stubbe. Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 |
| RNRs catalyze conversion of nucleotides to deoxynucleotides, an essential step in DNA replication and DNA repair.. Class I RNR is composed of two subunits: R1 and R2. R1 binds the NDP substrates and the allosteric effectors. R2 contains the diiron-tyrosyl radical (Y•) cofactor essential for initiation of thiyl radical (S•) formation on R1. The distance, proposed to be >35Å based on a docking model of R1 and R2, requires transient intermediates (amino acid radicals) to account for the turnover number of RNR. R2 has been synthesized semisynthetically to probe the mechanism of the radical intitation process. Studies using Y356-R2 analogs will be presented. They reveal that the Y731-Y730-C439 pathway in R1 likely involves H• transfer to generate the S•. The "pathway" in R2 likely does not involve direct coupling between the proton and ET, but is finely tuned by the pH dependence of the redox potentials of the Y122, Y356 and W48. |
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Alfred Bader Award in Bioinorganic or Bioorganic Chemistry
1:45 PM-5:00 PM, Monday, March 24, 2003 Convention Center -- La Nouvelle Ballroom A/B, Oral
Division of Organic Chemistry |