Hu S I, Pezacka E, Wood H G
J Biol Chem. 1984 Jul 25;259(14):8892-7.
A corrinoid protein has been purified from Clostridium thermoaceticum which is required for the synthesis of acetyl-CoA from carbon monoxide and methyltetrahydrofolate. The purified protein is an alpha beta dimer with subunit molecular weights of 34,000 and 55,000, respectively, and contains 0.69 mol of corrinoid/mol of dimer. The corrinoid protein is methylated in the presence of methyltransferase and methyltetrahydrofolate; methylation is on the cobalt of the corrinoid moiety of the protein. When 14C-methylated protein is incubated with Fraction F3, ATP, CoASH, and CO, [14C]acetyl-CoA is formed. Methylation of cobalamin (B12) is catalyzed by the methyltransferase but methylcobalamin does not substitute for the methylated corrinoid protein as the source of methyl in the formation of acetyl-CoA.
已从热醋梭菌中纯化出一种类咕啉蛋白，该蛋白是一氧化碳和甲基四氢叶酸合成乙酰辅酶A所必需的。纯化后的蛋白是一种αβ二聚体，亚基分子量分别为34,000和55,000，每摩尔二聚体含有0.69摩尔类咕啉。类咕啉蛋白在甲基转移酶和甲基四氢叶酸存在的情况下会发生甲基化；甲基化发生在蛋白类咕啉部分的钴上。当将14C甲基化的蛋白与F3组分、ATP、辅酶A和CO一起孵育时，会形成[14C]乙酰辅酶A。钴胺素（B12）的甲基化由甲基转移酶催化，但甲基钴胺素不能替代甲基化的类咕啉蛋白作为乙酰辅酶A形成过程中甲基的来源。
