Mehta Angad P, Abdelwahed Sameh H, Xu Hui, Begley Tadhg P
Department of Chemistry, Texas A & M University , College Station, Texas 77843, United States.
J Am Chem Soc. 2014 Jul 30;136(30):10609-14. doi: 10.1021/ja502663k. Epub 2014 Jul 18.
MoaA is a radical S-adenosylmethionine (AdoMet) enzyme that catalyzes a complex rearrangement of guanosine-5'-triphosphate (GTP) in the first step of molybdopterin biosynthesis. In this paper, we provide additional characterization of the MoaA reaction product, describe the use of 2'-chloroGTP to trap the GTP C3' radical, generated by hydrogen atom transfer to the 5'-deoxyadenosyl radical, and the use of 2'-deoxyGTP to block a late step in the reaction sequence. These probes, coupled with the previously reported trapping of an intermediate in which C3' of the ribose is linked to C8 of the purine, allow us to propose a plausible mechanism for the MoaA-catalyzed reaction.
MoaA是一种自由基S-腺苷甲硫氨酸（AdoMet）酶，在钼蝶呤生物合成的第一步中催化鸟苷-5'-三磷酸（GTP）的复杂重排反应。在本文中，我们对MoaA反应产物进行了补充表征，描述了使用2'-氯GTP捕获由氢原子转移至5'-脱氧腺苷自由基而产生的GTP C3'自由基，以及使用2'-脱氧GTP阻断反应序列中较晚步骤的情况。这些探针，再加上之前报道的对核糖C3'与嘌呤C8相连的中间体的捕获，使我们能够提出一种关于MoaA催化反应的合理机制。
