Isolation and properties of two phospholipases A2 from the venom of an Australian elapid snake (Pseudechis australis).
Two phospholipases A2 (Pa-11 and Pa-13) were purified from the venom of an Australian elapid snake (subfamily Acanthophiinae) Pseudechis australis (king brown snake) by chromatography on CM-cellulose CM-52 followed by gel filtration on a Sephadex G-75 column. The apparent molecular weights of the two phospholipases A2 (Pa-11 and Pa-13) were 14,000 and 13,500, respectively, by gel filtration analysis on a Sephadex G-75 column. Each enzyme molecule consists of a single polypeptide chain of 118 amino acid residues. The isoelectric points of Pa-11 and Pa-13 were 10.5 and 10.0, respectively. The optimum pH values of Pa-11 and Pa-13 for hydrolysis of egg-yolk phosphatidylcholine were 7.8 and 7.5, respectively. Pa-11 was lethal to mice (LD50 0.23 micrograms/g body weight), whereas Pa-13 showed no lethal activity at a dose level of 7.4 micrograms/g mouse. Each enzyme was inactivated by reaction with p-bromophenacylbromide on the sole histidine residue (Pa-11) or on one of the two histidine residues (Pa-13). Oxidation of the tryptophan residues in Pa-11 and Pa-13 with N-bromosuccinimide led to a decrease in the phospholipase A activity. A complete loss of both enzymic and lethal activities of Pa-11 was observed upon oxidation of one of the two tryptophan residues of the molecule.
D000098:Acetophenones; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001974:Bromosuccinimide; D002850:Chromatography, Gel; D003460:Crystallization; D004546:Elapid Venoms / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D007928:Lethal Dose 50; D051379:Mice; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010740:Phospholipases / Q000302:isolation & purification*; D010741:Phospholipases A / Q000302:isolation & purification* / Q000378:metabolism / Q000633:toxicity
D000098:Acetophenones; D000596:Amino Acids; D004546:Elapid Venoms; C026235:Pseudechis venom; D010740:Phospholipases; D010741:Phospholipases A; D001974:Bromosuccinimide; C006821:4-bromophenacyl bromide