The presence of Ca(2+)-independent phospholipase A1 highly specific for phosphatidylinositol in bovine brain.
EDTA-insensitive phospholipase A activity hydrolyzing phosphatidylinositol was detected in a bovine brain soluble fraction. This phospholipase A was purified 25-fold by sequential chromatographies of DEAE-Toyopearl, Phenyl-Toyopearl, and Ultrahydrogel 1000. The partially purified EDTA-insensitive phospholipase A showed an apparent molecular mass of 230kDa on an Ultrahydrogel 1000 column in the presence of 0.05% Triton X-100 and a pH optimum at 7.0. The enzyme was highly specific for phosphatidylinositol; phosphatidylethanolamine and phosphatidylcholine were not hydrolyzed significantly. The enzyme activity was characterized as phospholipase A1, and Ca2+ and Mg2+ were not required for its activity. These results indicate the existence of Ca(2+)-independent, phosphatidylinositol-specific metabolism besides those catalyzed by Ca(2+)-dependent phospholipase A2 and Ca(2+)-dependent, phosphatidylinositol-specific phospholipase C.
Ueda
H
H
Department of Biological Chemistry, Faculty of Pharmaceutical Sciences, Nagoya City University, Japan.
Kobayashi
T
T
Kishimoto
M
M
Tsutsumi
T
T
Watanabe
S
S
Okuyama
H
H
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism; D002122:Calcium Chloride / Q000494:pharmacology; D002417:Cattle; D004492:Edetic Acid / Q000494:pharmacology; D006868:Hydrolysis; D015636:Magnesium Chloride / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism*; D010741:Phospholipases A / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D054466:Phospholipases A1; D054467:Phospholipases A2; D013379:Substrate Specificity
D010716:Phosphatidylinositols; D015636:Magnesium Chloride; D004492:Edetic Acid; D010741:Phospholipases A; D054466:Phospholipases A1; D054467:Phospholipases A2; D002122:Calcium Chloride; D002118:Calcium