ZINC REQUIREMENT OF DINUCLEOTIDE PYROPHOSPHATASE IN MAMMALIAN ORGANS

The enzyme in unfractionated rat kidney which cleaves UDPG to yield glucose 1-phosphate is slowly and completely inactivated by polyacetic-acid-chelating agents and may be fully reactivated only by Zn2+ out of a total of eighteen cations tested. Imidazole also inactivates, but not by removal of a metal, and the effect is reversible by dilution alone. A smilar Zn2+ requirement was shown for the enzyme activity in eight other rat organs and the kidneys of eight other species. No difference in regard to inactivation and reactivation by Zn2+ was observed whether the substrate was UDPG, ADPG, CDPG, GDPG (rat kidney, liver, intestine and heart), DPN+ or FAD (rat kidney). Kinetic evidence indicates that, at least in rat kidney and liver, a single enzyme is responsible for the major activity toward UDPG and ADPG. © 1969.