title: The metal ion dependence of phospholipase C from Bacillus cereus.
abstract: 1. The zinc content and metal ion dependence of phospholipase C(phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3) from Bacillus cereus have been examined. 2. The native enzyme contained about 2 atoms of tightly bound zinc/molecule. 3. Incubation of the enzyme with EDTA or with o-phenanthroline caused inactivation. The inactivation was accompanied by the removal of one zinc atom from the enzyme and could be fully reversed by the addition of Zn2+ or Co2+ to the enzyme and partly reversed by Mn2+ or Mg2+. 4. Prolonged exposure to o-phenanthroline removed the second zinc atom also and produced an enzyme species which was reactivated by Zn2+ only. Full reactivation was accompanied by the binding of about two zinc atoms to the enzyme. 5. The results are consistent with the view that phospholipase C is a zinc metalloenzyme.
mesh_terms: D001409:Bacillus cereus / Q000187:drug effects / Q000201:enzymology*; D001665:Binding Sites; D003035:Cobalt / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008345:Manganese / Q000494:pharmacology*; D009154:Mutation; D010618:Phenanthrolines / Q000494:pharmacology; D010740:Phospholipases / Q000378:metabolism*; D011485:Protein Binding; D013997:Time Factors; D015032:Zinc / Q000494:pharmacology*
chemical_list: D010618:Phenanthrolines; D003035:Cobalt; D008345:Manganese; D004492:Edetic Acid; D010740:Phospholipases; D008274:Magnesium; D015032:Zinc