Ziegler M, Jorcke D, Herrero-Yraola A, Schweiger M
Freie Univ. Berlin, Institut f. Biochemie, Germany.
Adv Exp Med Biol. 1997;419:443-6.
Mitochondrial NAD+ glycohydrolase (NADase) has been proposed to be required for (nonenzymatic) ADP-ribosylation and subsequent activation of a Ca2+ release pathway. In our studies it has been found that several agents including nicotinamide, dithiothreitol, and EDTA exert no or little effect on ADP-ribosylation in isolated bovine liver mitochondria, while strongly inhibiting the NADase. The NADase did, however, catalyze the formation of cyclic purine nucleoside diphosphoriboses (similar to cyclic ADP-ribose) from NAD+ analogs. It appears possible, therefore, that this enzyme may be involved in the regulation of mitochondrial Ca2+ fluxes by forming a potent Ca(2+)-mobilizing agent, rather than by providing the substrate for non-enzymatic ADP-ribosylation.
线粒体NAD⁺糖水解酶（NADase）被认为是（非酶促）ADP核糖基化以及随后激活Ca²⁺释放途径所必需的。在我们的研究中发现，包括烟酰胺、二硫苏糖醇和EDTA在内的几种试剂对分离的牛肝线粒体中的ADP核糖基化没有影响或影响很小，同时却强烈抑制NADase。然而，NADase确实催化了NAD⁺类似物形成环状嘌呤核苷二磷酸核糖（类似于环状ADP核糖）。因此，这种酶似乎可能通过形成一种有效的Ca²⁺动员剂来参与线粒体Ca²⁺通量的调节，而不是通过为非酶促ADP核糖基化提供底物。
