title: The activation of phospholipase C from Clostridium Welchii by quinine: an absolute requirement for calcium ions.
abstract: Quinine activates the hydrolysis of phosphatidyl choline suspensions by phospholipase C (E.C. 3.1.4.3) obtained from Clostridium welchii. Low levels of calcium are an absolute requirement for this activation: Mg2+, Ba2+, Sr2+, and Zn2+ are ineffective. The induction period, or lag phase for this enzyme is dependent upon both calcium concentration and substrate interfacial surface area. At low concentrations (less then 50 muM) calcium ions affect the induction period but not the maximal rate of hydrolysis, whereas guinine predominantly affects the rate of hydrolysis by alterations in the surface charge carried by the substrate.
mesh_terms: D002118:Calcium / Q000494:pharmacology*; D002413:Cations, Divalent; D003016:Clostridium perfringens / Q000187:drug effects / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D010740:Phospholipases / Q000378:metabolism*; D011803:Quinine / Q000494:pharmacology*
chemical_list: D002413:Cations, Divalent; D004492:Edetic Acid; D011803:Quinine; D010740:Phospholipases; D002118:Calcium