来自旋盘尾丝虫和吉氏盘尾丝虫的磷酸烯醇丙酮酸羧激酶。

Phosphoenolpyruvate carboxykinase from Onchocerca volvulus and O. gibsoni.

作者信息

Walter R D, Albiez E J

出版信息

Trop Med Parasitol. 1986 Dec;37(4):356-8.

Abstract

Phosphoenolpyruvate carboxykinase, a rate-limiting enzyme at the branchpoint of phosphoenolpyruvate (PEP), was demonstrated in Onchocerca volvulus and O. gibsoni. The activity of PEP-carboxykinase from both filarial worms depends absolutely on the presence of divalent cations; in addition to Mg2+ the enzyme activity was strongly activated by Mn2+. The Michaelis constants for PEP, GDP and KHCO3 of the PEP-carboxykinase from O. volvulus were determined to be 0.16 mM, 0.15 mM and 20 mM, respectively; those of the enzyme from O. gibsoni were 0.16 mM, 0.13 mM and 12 mM. Quinolinate was found to be a potent inhibitor of the enzyme from both filarial worms. The inhibition constants were determined to be 11 microM and 15 microM for the enzyme from O. volvulus and O. gibsoni. It is suggested that the activity of PEP-carboxykinase, the initial enzyme of the alternate route from PEP to succinate, may be regulated by ATP-levels. The inhibition constants for ATP were determined to be 0.26 mM and 0.13 mM for the enzyme from O. volvulus and O. gibsoni.

摘要

磷酸烯醇丙酮酸羧激酶是磷酸烯醇丙酮酸（PEP）分支点处的一种限速酶，在旋盘尾丝虫和吉氏丝虫中得到了证实。两种丝虫的PEP羧激酶活性绝对依赖于二价阳离子的存在；除了Mg2+外，Mn2+也能强烈激活该酶的活性。旋盘尾丝虫的PEP羧激酶对PEP、GDP和KHCO3的米氏常数分别测定为0.16 mM、0.15 mM和20 mM；吉氏丝虫的该酶的米氏常数分别为0.16 mM、0.13 mM和12 mM。喹啉酸被发现是两种丝虫该酶的有效抑制剂。旋盘尾丝虫和吉氏丝虫该酶的抑制常数分别测定为11 microM和15 microM。有人提出，PEP羧激酶作为从PEP到琥珀酸的替代途径的起始酶，其活性可能受ATP水平的调节。旋盘尾丝虫和吉氏丝虫该酶对ATP的抑制常数分别测定为0.26 mM和0.13 mM。