Studies on phospholipase C from Pseudomonas aureofaciens. I. Purification and some properties of phospholipase C

Phospholipase C (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3) from Pseudomonas aureofaciens was purified 3600-fold from the culture filtrate with a recovery of 1.6%. Purification was performed with the useof (NH4)2SO4 precipitation, Sephadex G-100 gel filtration and by ion-exchange chromatography on DEAE-Sephadex A-50 and CM-Sephadex C-50. The purified enzyme appeared to be homogeneous as revealed by polyacrylamide disc gel electrophoresis at pH 9.3. The molecular weight was estimated to be 35 000 by gel filtration on Sephadex G-75. Under our experimental conditions, phosphatidylethanolamine was more rapidly hydrolysed than phosphatidylcholine. Lyso forms of these two phosphatides were poor substrates. Phosphatidylserine, phosphatidylglycerol, phosphatidylinositol, cardiolipin and sphingomyelin were not hydrolysed. The enzyme activity with phosphatidylcholine as substrate was slightly stimulated by Ca2+, Mg2+, and Mn2+. However, these cations inhibited the activity with phosphatidylethanolamine as substrate. An anionic detergent, sodium deoxycholate, slightly enhanced the activity when phosphatidylcholine and phosphatidylethanolamine were used as substrates. A cationic detergent, cetyltrimethylammonium bromide, inhibited enzyme activity. EDTA and o-henanthroline inhibited the activity of the enzyme to a marked degree.