EPR distance measurements support a model for long-range radical initiation in E. coli ribonucleotide reductase.
The class I E. coli ribonucleotide reductase, composed of homodimers of R1 and R2, catalyzes the conversion of nucleoside diphosphates to deoxynucleoside diphosphates. The reduction process involves the tyrosyl radical on R2 that generates a transient thiyl radical on R1 over a proposed distance of 35 A. A mechanism-based inhibitor, 2'-azido-2'-deoxyuridine-5'-diphosphate, that reduces the tyrosyl radical on R2 and forms a nitrogen-centered radical on R1 has provided a method to measure the diagonal distance between the two subunits. PELDOR and DQC paramagnetic resonance methods give rise to a distance of 48 A, similar to that calculated from a docking model of the R1 and R2 structures.
Bennati
Marina
M
Institute of Physical and Theoretical Chemistry and BMRZ, University of Frankfurt, D-60439 Frankfurt, Germany. bennati@chemie.uni-frankfurt.de
Robblee
John H
JH
Mugnaini
Veronica
V
Stubbe
Joanne
J
Freed
Jack H
JH
Borbat
Peter
P
D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D004926:Escherichia coli / Q000201:enzymology*; D005609:Free Radicals / Q000737:chemistry*; D008954:Models, Biological; D012264:Ribonucleotide Reductases / Q000378:metabolism*; D013997:Time Factors
D005609:Free Radicals; D012264:Ribonucleotide Reductases