Partial purification of phosphoinositide phospholipase C from human platelet cytosol; characterization of its three forms.
Three forms (I, IIa and IIb) of phospholipase C, hydrolyzing specifically inositol phospholipids, were resolved from human platelet cytosol and partially purified by DEAE-cellulose, phenyl-Sepharose, Ultrogel ACA-44 and hydroxylapatite column chromatographies. All three forms exhibited pH optimum at 6.5 - 7.0 in the presence of deoxycholate and their molecular weights were 67,000 (form I), 120,000 (IIa) and 70,000 (IIb). These enzymes hydrolyzed both phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate in Ca2+-dependent manner; their maximal activities for phosphatidylinositol hydrolysis were obtained at 10(-4) to 10(-3) M Ca2+, whereas phosphatidylinositol 4,5-bisphosphate was preferentially hydrolyzed at lower concentration of Ca2+.
D001792:Blood Platelets / Q000201:enzymology*; D002118:Calcium / Q000494:pharmacology; D002845:Chromatography; D003600:Cytosol / Q000201:enzymology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008970:Molecular Weight; D019269:Phosphatidylinositol 4,5-Diphosphate; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010716:Phosphatidylinositols / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000097:blood*
D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D010727:Phosphoric Diester Hydrolases; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D002118:Calcium