四磷酸二腺苷激活胞质5'-核苷酸酶。

Diadenosine tetraphosphate activates cytosol 5'-nucleotidase.

作者信息

Pinto R M, Canales J, Günther Sillero M A, Sillero A

出版信息

Biochem Biophys Res Commun. 1986 Jul 16;138(1):261-7. doi: 10.1016/0006-291x(86)90274-3.

Abstract

The rate of hydrolysis of IMP (0.5 mM) by cytosol 5'-nucleotidase from Artemia embryos was increased up to 7-fold by concentrations of around 10 microM diadenosine tetraphosphate (Ap4A). Half maximal activation of the enzyme was accomplished with 5 microM Ap4A. The Km (S 0.5) values of the nucleotidase for IMP, GMP, AMP, XMP and CMP decreased about 10 fold in the presence of 10 microM Ap4A. Maximum velocity of the enzyme was not affected by Ap4A. ATP had been previously described as an activator of the enzyme. However, comparatively with Ap4A, concentrations of ATP two orders of magnitude higher are needed to elicit similar effects on the enzyme. Preliminary results indicate that Ap4A is also an activator of the cytosol 5'-nucleotidase from rat liver.

摘要

卤虫胚胎胞质5'-核苷酸酶对IMP（0.5 mM）的水解速率在浓度约为10 microM的四磷酸二腺苷（Ap4A）作用下提高了7倍。该酶的半最大激活浓度为5 microM Ap4A。在存在10 microM Ap4A的情况下，核苷酸酶对IMP、GMP、AMP、XMP和CMP的Km（S 0.5）值降低了约10倍。酶的最大反应速度不受Ap4A影响。ATP此前已被描述为该酶的激活剂。然而，与Ap4A相比，需要两个数量级更高浓度的ATP才能对该酶产生类似的作用。初步结果表明，Ap4A也是大鼠肝脏胞质5'-核苷酸酶的激活剂。