title: Phospholipase A of sea snake Laticauda semifasciata venom. Isolation and properties of novel forms lacking tryptophan.
abstract: The venom gland extracts of the sea snake Laticauda semifasciata contained at least four forms of phospholipase A separable on a CM-cellulose column. They were designated as phospholipases A I-IV in the order of elution from the column. Phospholipases A I, III, and IV were isolated in a homogeneous state. They were similar to one another in amino acid composition and molecular weight (14,000) as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Phospholipase A I contained one tryptophan residue. whereas III and IV did not. Although all these forms had the same A2-type positional specificity, they were classified into two groups (I, and III and IV) on the basis of enzymic properties. Phospholipase A I had a higher specific activity and showed normal kinetics, whereas III and IV had approximately one-tenth of the specific activity of I and showed biphasic kinetics due to their activation by the reaction products. Phospholipase A I, the major form, seems to be identical with phospholipase A reported previously (Tu, A.T., Passey, R.B., & Toom, P.M. (1970) Arch. Biochem. Biophys. 140, 96-106), whereas the other two, III and IV, are new. Phospholipase A I became more like III and IV in enzymic properties on modification with N-bromosuccinimide.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D004546:Elapid Venoms / Q000302:isolation & purification; D005227:Fatty Acids / Q000032:analysis; D006801:Humans; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D010740:Phospholipases / Q000302:isolation & purification / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000596:Amino Acids; D004546:Elapid Venoms; D005227:Fatty Acids; D007527:Isoenzymes; D010740:Phospholipases; D002118:Calcium