DETECTION OF 2 PHOSPHOLIPASE A(2)(PLA(2)) ACTIVITIES IN LEAVES OF HIGHER-PLANT VICIA-FABA AND COMPARISON WITH MAMMALIAN PLA(2)S

Abstract

Leaves of higher plant Vicia faba contains two Phospholipase A(2)(PLA(2)) activities which are detected in cytosolic fractions. Based on a gel filtration column chromatography, two cytosolic PLA, activities migrated with molecular masses of 70 kDa and 14 kDa. The first (70 kDa peak) was optimally active at pH 4.5 and was not dependent on [Ca2+] for its activity. In the presence of 5 mM CaCl2, 'phospholipase B' activity was shown in the 70 kDa peak. The second (14 kDa peak) was optimally active in the pH range 9-10 and required millimolar concentrations of calcium for optimal activity. The two activities were not inhibited by dithiothreitol. Neither anti-pancreatic PLA(2) antiserum nor anti-(pig spleen 100 kDa cytosolic PLA(2)) antiserum immunoprecipitated any activity of the two plant PLA(2)'s. The present results indicate that at least the 14 kDa form of the two PLA(2) enzymes detected in leaves of higher plants is biochemically and immunochemically different from the well characterized Ca2+-dependent mammalian PLA(2)'s.