Vitamin B12 Biosynthesis: in vitro formation of cobinamide from cobyric acid and L-threonine.
Vitamin B12 Biosynthesis: in vitro formation of cobinamide from cobyric acid and L-threonine.
复制标题
维生素 B12 生物合成：在体外由钴酸和 L-苏氨酸形成钴酰胺。
DOI：
10.1016/0003-9861(76)90490-2
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发表时间：
1976
影响因子：
3.9
通讯作者：
Herbert C. Friedmann
中科院分区：
文献类型：
--
作者：
Susan H. Ford;Herbert C. Friedmann
钴胺素产生菌Propionibacterium shermaniiiatesl-苏氨酸转化为corrinoids最有力的早期生长阶段。利用早期生长细菌的无细胞提取物获得了一个体外系统，该系统在苏氨酸存在下将钴酸转化为钴氨酰胺和由钴氨酰胺形成的生物合成产物。由于在粗提物中l-苏氨酸不仅作为类咕啉组分（R）-1-氨基-2-丙醇的来源，而且经历与类咕啉形成无关的广泛代谢变化，因此体外系统的研究需要使用14 C标记的Co-β-腺苷酸和未标记的l-苏氨酸。当还原剂如谷胱甘肽和能量源如ATP或磷酸烯醇丙酮酸和丙酮酸激酶存在时，Cobyric酸向Cobinamide的体外转化增加。利用部分纯化的酶组分，可以使用14 C-标记的l-苏氨酸和未标记的Coβ-腺苷钴酸来研究钴氨酰胺的形成。
The cobalamin-producing bacteriumPropionibacterium shermaniiincorporatesl-threonine into corrinoids most vigorously during the early growth phase. Anin vitrosystem, utilizing cell-free extracts from the early-growth bacteria has been obtained which in the presence ofl-threonine converts cobyric acid into cobinamide and biosynthetic products formed from cobinamide. Since in crude extractsl-threonine functions not only as the source of the corrinoid constituent (R)-1-amino-2-propanol but undergoes extensive metabolic changes unrelated to corrinoid formation, the study of thein vitrosystem required the use of14C-labeled Coβ-adenosylcobyric acid and unlabeledl-threonine. Thisin vitroconversion of cobyric acid to cobinamide is increased when a reductant such as glutathione and an energy source such as ATP, or phosphoenolpyruvate and pyruvate kinase, are present as well. With a partially purified enzyme fraction cobinamide formation could be studied using14C-labeledl-threonine and unlabeled Coβ-adenosylcobyric acid.