Osamu Doi

Phospholipase C from pseudomonas fluorescens

Abstract Phospholipase C found in the growth medium of Pseudomonas fluorescens was purified 2500-fold by (NH4)2SO4 fractionation and successive chromatography on Sephadex G-100, Sephadex G-200 and DEAE-Sephadex A-50 columns. Phosphatidyl ethanolamine rather than phosphatidyl choline was hydrolyzed extensively under our experimental conditions. Lysophosphatidyl ethanolamine, phosphatidyl glycerol and cardiolipin were poor substrates. The purified preparation had a specific activity of 36.5 μmoles per min per mg of protein toward phosphatidyl ethanolamine. This phospholipase C was shown to be a typical extracellular enzyme.

Solubilization and properties of a phosphatidylethanolamine-dependent methyltransferase system for phosphatidylcholine synthesis from mouse liver microsomes.

Summary A method was developed for solubilization of a phosphatidylethanolamine-dependent methyltransferase system for phosphatidylcholine synthesis in mouse liver microsomes. A preparation with high specific activity was obtained in good yield by treating 0.3% deoxycholate-treated microsomes with 0.2% Triton X-100. With this preparation, methyl incorporation into phospholipids was activated by phosphatidylethanolamine and its methylated intermediates. The specific activity of the preparation with phosphatidylethanolamine was 4 times that of intact microsomes. The reaction products with the solubilized preparation were phosphatidylcholine and methylated intermediates of phosphatidylethanolamine.

Growth of bacteriophage lambda in phospholipases A-less mutants

Summary E. coli mutants defective in dr - and dr and ds -phospholipases A support the normal growth of bacteriophage lambda. The time of cell lysis and the burst size were similar to those in the infected wild-type cells. In contrast to the wild-type cells, however, any significant release of fatty acids from 14C-acetate prelabeled phospholipids was observed at the time of lysis. The release of fatty acids in the wild-type cells appears to be caused by dr -phospholipase A.