EPR Distance Measurements Support a Model for Long-Range Radical Initiation in E. coli Ribonucleotide Reductase

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• 作者：Marina Bennati ; John H. Robblee ; Veronica Mugnaini ; Joanne Stubbe ; Jack H. Freed ; and Peter Borbat
• 刊名：Journal of the American Chemical Society
• 出版年：2005
• 出版时间：November 2, 2005
• 年：2005
• 卷：127
• 期：43
• 页码：15014 - 15015
• 全文大小：128K
• 年卷期：v.127,no.43(November 2, 2005)
• ISSN：1520-5126

文摘

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 Å. 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 Å, similar to that calculated from a docking model of the R1 and R2 structures.