Lawrence C C, Stubbe J
Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139, USA.
Curr Opin Chem Biol. 1998 Oct;2(5):650-5. doi: 10.1016/s1367-5931(98)80097-5.
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.
来自赖氏乳杆菌的核糖核苷三磷酸还原酶催化核苷酸还原为脱氧核苷酸，并使用腺苷钴胺素作为辅因子。一种基于蛋白质的瞬态硫自由基对于催化作用至关重要。旨在阐明腺苷钴胺素在催化过程中功能的研究表明，硫自由基和5'-脱氧腺苷的形成与C-Co键均裂协同发生，均裂是由熵驱动而非焓驱动的，腺苷钴胺素的二甲基苯并咪唑部分在催化过程中是轴向配体，并且每次周转后C-Co键都会重新形成。
