Biosynthesis of pteridines -: NMR studies on the reaction mechanisms of GTP cyclohydrolase I, pyruvoyltetrahydropterin synthase, and sepiapterin reductase
Biosynthesis of pteridines -: NMR studies on the reaction mechanisms of GTP cyclohydrolase I, pyruvoyltetrahydropterin synthase, and sepiapterin reductase
复制标题
DOI：
10.1074/jbc.273.43.28132
复制
发表时间：
1998-10-23
影响因子：
4.8
通讯作者：
Bacher, A
中科院分区：
文献类型：
--
作者：
Bracher, A;Eisenreich, W;Bacher, A
GTP cyclohydrolase I catalyzes a ring expansion affording dihydroneopterin triphosphate from GTP. [1',2',3',4',5'-C-13(5),2'-H-2(1)]GTP was prepared enzymatically from [U-C-13(6)]glucose for use as enzyme substrate. Multinuclear NMR experiments showed that the reaction catalyzed by GTP cyclohydrolase I involves the release of a proton from C-2' of GTP that is exchanged with the bulk solvent. Subsequently, a proton is reintroduced stereospecifically from the bulk solvent. This is in line with an Amadori rearrangement mechanism. The proton introduced from solvent occupies the pro-7R position in the enzyme product. The data also confirm that the reaction catalyzed by pyruvoyltetrahydropterin synthase results in the incorporation of solvent protons into positions C-6 and C-3' of the enzyme product. On the other hand, the reaction catalyzed by sepiapterin reductase does not involve any detectable incorporation of solvent protons into tetrahydrobiopterin.
