The function of adenosylcobalamin in the mechanism of ribonucleoside triphosphate reductase from Lactobacillus leichmannii

✍ Scribed by Christopher C Lawrence; JoAnne Stubbe

• Book ID: 104415080
• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 681 KB
• Volume: 2
• Category: Article
• ISSN: 1367-5931
• DOI: 10.1016/s1367-5931(98)80097-5

✦ Synopsis

Ribonucleoside triphosphate reductase from Lactobacillus leichmannii catalyzes the reduction of nucleotides to deoxynucleotides and uses adenosylcobalamin as a cofactor. A transient protein-based thiyl radical is essential for catalysis. Studies directed toward the elucidation of the function of adenosylcobalamin during catalysis have shown that formation of the thiyl radical and 5'-deoxyadenosine occurs in a concerted fashion with C-Co bond homolysis, that the homolysis is entropically and not enthalpically driven, that the dimethylbenzimidazole moiety of adenosylcobalamin is the axial ligand during catalysis, and that the C-Co bond is reformed after every turnover.