Cornish R A, Wilkes J, Mettrick D F
Mol Biochem Parasitol. 1981 Feb;2(3-4):151-66. doi: 10.1016/0166-6851(81)90096-7.
Procedures have been developed for the extraction and subsequent purification of the enzyme phosphoenolpyruvate carboxykinase (GTP) (PEPCK) from Moniliformis dubius (Acanthocephala), a parasite of the rat small intestine. This is believed to be the first purification of PEPCK from an invertebrate animal. The enzyme, when purified to homogeneity as indicated by electrophoretic criteria, has a molecular weight of 73 700. Kinetic studies indicated that the enzyme had a pH optimum of 5.5 and required Mn2+ as the divalent cation. The apparent Km values determined for the substrates of the carboxylation reaction were low compared with the published values for purified PEPCK from vertebrate sources. Several competitive inhibitors were found and their Ki values determined. The possible regulation of PEPCK activity in M. dubius is discussed with reference to the observed kinetic parameters.
已经开发出了从大鼠小肠寄生虫——念珠棘虫（棘头虫纲）中提取并随后纯化磷酸烯醇丙酮酸羧激酶（GTP）（PEPCK）的方法。据信这是首次从无脊椎动物中纯化出PEPCK。通过电泳标准表明该酶纯化至同质时，其分子量为73700。动力学研究表明该酶的最适pH为5.5，并且需要Mn2+作为二价阳离子。与已发表的来自脊椎动物来源的纯化PEPCK的值相比，羧化反应底物的表观Km值较低。发现了几种竞争性抑制剂并测定了它们的Ki值。参考观察到的动力学参数讨论了念珠棘虫中PEPCK活性的可能调节。
