title: Purification and characterization of a novel phospholipase A2 from king cobra (Ophiophagus hannah) venom.
abstract: A novel phospholipase A2, designated as Oh-DE-2, was isolated from the venom of Ophiophagus hannah (king cobra) by successive chromatography on SP-Sephadex C-25, DE-52, and Q-Sepharose columns. Oh-DE-2 with pI 5.1 showed an apparent molecular weight of 14 kD as revealed by SDS-PAGE and gel filtration. The amino acid sequence was homologous with those of PLA2S from Elapidae venoms. Oh-DE-2 was effectively inactivated by p-bromophenacyl bromide, indicating that the conserved His-48 is essential for its enzymatic activity. However, modification of the conserved Trp-19 did not cause a precipitous drop in the enzymatic activity of Oh-DE-2 as observed with PLA2S from Naja naja atra and Bungarus multicinctus venoms. A quenching study showed that the microenvironment of Trp in Oh-DE-2 was inaccessible to acrylamide, iodide, or cesium, a finding which was different from those observed with PLA2S from N. naja atra and B. multicinctus venoms. These results might suggest that, unlike other PLA2 enzymes, Trp-19 in Oh-DE-2 is not directly involved in its enzymatic mechanisms.
authors.affiliation: Department of Biochemistry, Kaohsiung Medical College, Taiwan, ROC.
authors.forename: J Y
authors.initials: JY
authors.lastname: Chiou
authors.forename: L S
authors.initials: LS
authors.lastname: Chang
authors.forename: L N
authors.initials: LN
authors.lastname: Chen
authors.forename: C C
authors.initials: CC
authors.lastname: Chang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004546:Elapid Venoms / Q000201:enzymology*; D008969:Molecular Sequence Data; D010741:Phospholipases A / Q000032:analysis / Q000302:isolation & purification*; D054467:Phospholipases A2; D017386:Sequence Homology, Amino Acid
chemical_list: D004546:Elapid Venoms; D010741:Phospholipases A; D054467:Phospholipases A2