Tkachuck R D, Saz H J, Weinstein P P, Finnegan K, Mueller J F
J Parasitol. 1977 Oct;63(5):769-74.
Both spargana and adult forms of Spirometra mansonoides were shown to accumulate lactate, succinate, acetate, and propionate upon in vitro incubation. Adults differed markedly from the spargana in that quantitatively the most significant products of the former were acetate and propionate while the latter formed primarily acetate and lactate. The adults accumulated approximately 32 times more propionate than the spargana per gram of tissue. In accord with this propionate formation, propionyl CoA carboxylase and methylmalonyl CoA mutase have been found to be present in both stages of the parasite. As might be predicted, however, the activities of the carboxylase and mutase were 100-fold and 10-fold higher, respectively, in the adults as compared to the larvae. A possible physiological relationship between propionate formation and energy generation is suggested. Accordingly, inorganic 32P was incorporated into ATP upon incubation of methylmalonyl CoA with a homogenate obtained from adult S. mansonoides. Since methylmalonyl CoA mutase requires vitamin B12 coenzyme, a relationship between vitamin B12 content and propionate formation in helminths is suggested.
曼氏迭宫绦虫的裂头蚴和成虫在体外培养时均能积累乳酸、琥珀酸、乙酸和丙酸。成虫与裂头蚴有显著差异，前者在数量上最主要的产物是乙酸和丙酸，而后者主要生成乙酸和乳酸。每克组织中，成虫积累的丙酸比裂头蚴多约32倍。与这种丙酸生成一致，在寄生虫的两个阶段均发现存在丙酰辅酶A羧化酶和甲基丙二酰辅酶A变位酶。然而，可以预料的是，与幼虫相比，成虫中羧化酶和变位酶的活性分别高100倍和10倍。提示了丙酸生成与能量产生之间可能的生理关系。因此，将甲基丙二酰辅酶A与曼氏迭宫绦虫成虫匀浆一起孵育时，无机32P被掺入ATP中。由于甲基丙二酰辅酶A变位酶需要维生素B12辅酶，提示了蠕虫中维生素B12含量与丙酸生成之间的关系。
