title: Evidence that the peripheral cyclic AMP phosphodiesterase of rat liver plasma membranes is a metalloenzyme.
abstract: Cyclic nucleotide phosphodiesterase activity in salt extracts of rat liver plasma membranes was progressively inactivated by treatment with the metal chelators 8-hydroxyquinoline and o-phenanthroline, but not the non-chelating m-phenanthroline isomer. Activity at 20 microM-cyclic AMP was lost more slowly than activity at 0.4 microM-cyclic AMP. The activity of treated preparations was partially restored by incubation with Zn2+ or Mn2+ ions (in the presence of 1 mM-MgCl2) but not with Ca2+, Cd2+, Co2+, Cu2+ or Fe2+ ions, nor by MgCl2 alone. The results suggest the presence in the membrane extracts of a cyclic AMP phosphodiesterase containing tightly bound metal, possibly Zn or Mn, that affects the enzyme's affinity for cyclic AMP.
authors.forename: J
authors.initials: J
authors.lastname: Londesborough
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008670:Metals / Q000494:pharmacology*; D015125:Oxyquinoline / Q000494:pharmacology; D010618:Phenanthrolines / Q000494:pharmacology; D051381:Rats; D015032:Zinc / Q000494:pharmacology
chemical_list: D008670:Metals; D010618:Phenanthrolines; D015125:Oxyquinoline; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D015032:Zinc; C025205:1,10-phenanthroline