Isolation and properties of lysophospholipases from the venom of an Australian elapid snake, Pseudechis australis

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Abstract
Two similar lysophospholipases were isolated from the venom of an Australian elapid snake (Acanthophiinae), P. australis, by sequential chromatography on CM-52 cellulose, Sephadex G-75 and DE-52 cellulose columns. Lysophospholipase 1 was obtained as a homodimer, the monomer of which consisted of 123 amino acid residues with 7 disulfide bridges. The amino acid composition and the N-terminal amino acid sequence of the enzyme were similar to those of phospholipase A2. Ca2+ was required for its activity and the maximum activity was attained at 2 mM CaCl2 in the presence of 1 mM EDTA. The optimum pH was 7.5. Lysophospholipase 1 hydrolyzed lysophosphatidylcholine more rapidly than lysophosphatidylethanolamine. It did not hydrolyze phosphatidylcholine, 1-palmitoylglycerol, tripalmitoylglycerol or p-nitrophenyl acetate. Modification of the enzyme with p-bromophenacyl bromide or 2-nitrophenylsulfenyl chloride suppressed the activity. A strong direct hemolytic activity was exhibited when the lysophospholipase was present together with phospholipase A2.