| Popis: |
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. |
