Abstract
A marine snail digestive phospholipase A(2) (mSDPL) was purified from delipidated hepatopancreas. Unlike known digestive phospholipases A(2), which are 14 kDa proteins, the purified mSDPL has a molecular mass of about 30 kDa. It has a specific activity of about 180 U/mg measured at 50 degrees C and pH 8.5 using phosphatidylcholine liposomes as a substrate in the presence of 4 mM NaTDC and 6 mM CaCl2. The N-terminal amino-acid of the purified mSDPL does not share any homology with known phospholipases.
Moreover, the mSDPL exhibits hemolytic activity in intact erythrocytes and can penetrate phospholipid monolayers at high surface pressure, comparable to snake venom PLA(2). These observations suggest that mSDPL could be toxic to mammal cells. However, mSDPL can be classified as a member of a new family of enzymes. It should be situated between the class of toxic phospholipase A(2) from venoms and another class of non toxic pancreatic phospholipase A(2) from mammals. (C) 2009 Elsevier Inc. All rights reserved.