THE SYNTHETIC SUBSTRATE SUCCINYL(CARBADETHIA)-COA GENERATES COB(II)ALAMIN ON ADENOSYLCOBALAMIN-DEPENDENT METHYLMALONYL-COA MUTASE
THE SYNTHETIC SUBSTRATE SUCCINYL(CARBADETHIA)-COA GENERATES COB(II)ALAMIN ON ADENOSYLCOBALAMIN-DEPENDENT METHYLMALONYL-COA MUTASE
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DOI：
10.1042/bj2950387
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发表时间：
1993-10-15
影响因子：
4.1
通讯作者：
LEADLAY, PF
中科院分区：
文献类型：
--
作者：
KEEP, NH;SMITH, GA;LEADLAY, PF
琥珀酰（卡巴硫）辅酶A，腺苷钴胺素依赖性甲基丙二酰辅酶A的合成底物，已通过简化的程序制备。当重组底物与合成底物混合时，u. v./结合辅因子的可见吸收光谱迅速变化，类似于cob（II）alamin的吸收光谱。在467 nm处具有最大吸收。添加天然底物。与此相反。在u. v./可见光谱。最近的一个复杂的电子病历的生成报告。用重组酶证实了向全甲基丙二酰辅酶A底物中加入底物的光谱。当使用琥珀酰（卡巴地亚）类似物时，观察到的信号更强。钴K-边X-射线吸收光谱证实，除了这种类似物全酶导致产生的钴（II）丙氨酸类物种。这些结果强烈支持在甲基丙二酰辅酶A变位酶催化的1，2-骨架重排过程中产生辅酶（II）丙氨，如果这种酶遵循涉及先前为其他腺苷钴胺素依赖性酶提出的自由基中间体的反应途径，则需要这样的结果。
Succinyl(carbadethia)-coenzyme A, a synthetic substrate for adenosylcobalamin-dependent methylmalonyl-CoA mutase, has been prepared by a simplified procedure. When recombinant mutase was mixed with the synthetic substrate, the u.v./visible absorption spectrum of the bound cofactor changed rapidly to resemble that of cob(II)alamin. with an absorption maximum at 467 nm. Addition of the natural substrates. in contrast. produced only minor changes in the u.v./visible spectrum. The recent report of the generation of a complex e.p.r. spectrum on addition of substrate to the holo-methylmalonyl-CoA mutase was confirmed with the recombinant enzyme. The signals observed were stronger when the succinyl(carbadethia) analogue was used. Cobalt K-edge X-ray absorption spectroscopy confirmed that the addition of this analogue to holoenzyme leads to the generation of a cob(II)alamin-like species. These results strongly support the generation of cob(II)alamin during the 1,2-skeletal rearrangement catalysed by methylmalonyl-CoA mutase, as required if this enzyme follows the reaction pathway involving radical intermediates previously proposed for other adenosyl-cobalamin-dependent enzymes.