Saz H J, deBruyn B S
J Exp Zool. 1987 May;242(2):241-5. doi: 10.1002/jez.1402420215.
Many invertebrates accumulate propionate, or products derived from propionate, as products of fermentation. Evidence has been reported that the nematode, Ascaris suum, the cestode, Spirometra mansonoides, and the trematode, Fasciola hepatica, accumulate propionate by means of an adenosine triphosphate (ATP)-generating decarboxylation of succinate. To generate energy, an acyl coenzyme A (CoA) transferase that would transfer CoA to succinate is required as one component of the sequence of reactions. Recently, an acyl CoA transferase was isolated from Ascaris mitochondria and purified to electrophoretic homogeneity. However, upon examination of the substrate specificities of this enzyme, it was found essentially to lack the ability to use succinate or succinyl CoA as an acceptor or donor of CoA, respectively. Therefore, this transferase could not serve to activate succinate. This article describes the isolation of an additional acyl CoA transferase from Ascaris mitochondria that appears to be unique in its substrate specificity and that could easily account not only for the activation of succinate but also for the regulation of succinate metabolism primarily in the direction of decarboxylation to propionate. This is in contrast with mammalian tissues, which act in the opposite direction by catalyzing the fixation of CO2 into propionate, thereby forming succinate and accounting for the glycogenic nature of dietary propionate. Possible functions of the two acyl CoA transferases are discussed.
许多无脊椎动物会积累丙酸或丙酸衍生的产物，作为发酵产物。有证据表明，线虫猪蛔虫、绦虫曼氏迭宫绦虫和吸虫肝片吸虫通过琥珀酸的生成三磷酸腺苷（ATP）的脱羧作用来积累丙酸。为了产生能量，作为反应序列的一个组成部分，需要一种将辅酶A（CoA）转移到琥珀酸的酰基辅酶A转移酶。最近，从蛔虫线粒体中分离出一种酰基辅酶A转移酶，并将其纯化至电泳纯。然而，在检测这种酶的底物特异性时，发现它基本上分别缺乏将琥珀酸或琥珀酰辅酶A用作辅酶A受体或供体的能力。因此，这种转移酶不能用于激活琥珀酸。本文描述了从蛔虫线粒体中分离出的另一种酰基辅酶A转移酶，其底物特异性似乎很独特，不仅可以很容易地解释琥珀酸的激活，还可以解释琥珀酸代谢主要朝着脱羧生成丙酸方向的调节。这与哺乳动物组织相反，哺乳动物组织通过催化二氧化碳固定到丙酸中，从而形成琥珀酸，并解释了膳食丙酸的糖原生成性质，其作用方向相反。文中讨论了这两种酰基辅酶A转移酶的可能功能。
