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首页> 外文期刊>Chemistry: A European journal >Synthesis of Enantiomerically-Pure [~13C]Aristeromycyclocobalamin and Its Reactivit in Dioldehydratase, Glyceroldehydratase, Ethanolamine Ammonia-Lyase and Methylmalonyl-CoA Muase Reactions
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Synthesis of Enantiomerically-Pure [~13C]Aristeromycyclocobalamin and Its Reactivit in Dioldehydratase, Glyceroldehydratase, Ethanolamine Ammonia-Lyase and Methylmalonyl-CoA Muase Reactions

机译：对映体纯的[〜13C]芳香环钴胺素的合成及其在二聚脱水酶，甘油二聚脱水酶，乙醇胺氨解酶和甲基丙二酰辅酶A发生的反应中的活化

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摘要

We describe a novel enantioselective synthesis of aristeromycin, the carbocyclic analogue of adenosine. The seven-step synthesis is also suitable for the preparation of specifically-labelled [6'-~13C]aristeromycin. Both the unlabelled and ~13C-labelled product was coupled to vitamin B_12 to form aristeromycyclobalamin. This carbocyclic analogue of coenzyme B_12 was examined for its coenzymic activity with several adenosylcobalamin-dependent enzymes. For glyceroldelhydrates and dioldehydratase, the reaction rate (k_cat) was 38 and 44% of that measured with adenosylcobalamin as coenzyme. In contrast, aristeromycyclobalamin showed no detect-able activity with methylmalonyl-CoA mutase and ethanolamine ammonia-lyase. Instead, it was a weak inhibitor of the former and a strong inhibitor of the latter enzyme. The slower turnover rate with glyceroldehydratase raised the hope of detecting the 6'-deoxyaristeromycycl radical intermediate. Comparison of the ERP spectra of the intermediates in the glyceroldehydratase reaction, which used adenosyl-and aristeromycyclobalamines, respectively, as coenzyme, revealed a significant shift and this suggests a different geometric position of these cofactors at the binding site during the cleavage of the carbon-cobalt bond. However, we found no evidence for the existence of a 6'-deoxyaristeromycyl radical during the reaction with [6'-~13C]aristeromycyclobalamin. We conclude that the lifetime of this radical is still too short to be observed.
机译：我们描述了一种新型的对映选择性合成的阿霉素，腺苷的碳环类似物。七步合成法也适用于制备特异性标记的[6'-〜13C]阿霉素。未标记和〜13C标记的产品均与维生素B_12偶联形成环孢菌素。检查了辅酶B_12的碳环类似物与几种腺苷钴胺素依赖性酶的辅酶活性。对于甘油三水合物和二醇脱水酶，反应速率（k_cat）是用腺苷钴胺素作为辅酶测得的反应速率的38和44％。相比之下，aristeromycyclobalamin对甲基丙二酰辅酶A变位酶和乙醇胺氨裂解酶未显示可检测的活性。相反，它是前一种酶的弱抑制剂和后一种酶的强抑制剂。甘油三糖水合酶的较慢周转率提高了检测6'-deoxyaristeromycycl自由基中间体的希望。分别使用腺苷和Aristeromycyclobalbalamines作为辅酶的甘油三水合酶反应中的中间体的ERP谱图的比较显示了显着的变化，这表明这些辅因子在碳原子裂解过程中在结合位点的几何位置不同。钴键。然而，我们没有发现与[6'~~ 13C]芳环菌素相关的反应过程中存在6'-脱氧芳菊基自由基的证据。我们得出结论，该自由基的寿命仍然太短而无法观察。

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