Tkachuck R D, Weinstein P P, Mueller J F
J Parasitol. 1977 Aug;63(4):694-700.
Analysis of tissue from Spirometra mansonoides spargana has shown that cyanocobalamin (vitamin B12) is metabolized to adenosylcobalamin and hydroxocobalamin. No methylcobalamin was detected. When the tissues were examined for enzymes which are known to utilize coenzyme forms of vitamin B12, only methylmalonyl CoA mutase, which requires adenosylcobalamin was found. The enzyme, tetrahydropteroylglutamate methyltransferase, which requires methylcobalamin as a cofactor, was not detected. A sizable portion of the cyanocobalamin taken up was bound to ammonium sulfate-precipitable material, suggesting that the binding substance is a protein. Vitamin B12 taken up by spargana was found to be released in vivo with a biological half-life of about 7 weeks.
对曼氏迭宫绦虫裂头蚴组织的分析表明，氰钴胺素（维生素B12）可代谢为腺苷钴胺素和羟钴胺素。未检测到甲基钴胺素。当检测这些组织中已知利用维生素B12辅酶形式的酶时，仅发现了需要腺苷钴胺素的甲基丙二酰辅酶A变位酶。未检测到需要甲基钴胺素作为辅因子的四氢蝶酰谷氨酸甲基转移酶。所摄取的相当一部分氰钴胺素与硫酸铵可沉淀物质结合，这表明结合物质是一种蛋白质。发现裂头蚴摄取的维生素B12在体内释放，生物半衰期约为7周。
