title: Purification, sequencing and characterization of pseudexin phospholipases A2 from Pseudechis porphyriacus (Australian red-bellied black snake).
abstract: Pseudexin is the name given to a mixture of toxic phospholipase A2 isoenzymes isolated from the venom of the Australian red-bellied black snake, Pseudechis porphyriacus. We found that this mixture consists of three components: pseudexins A, B and C, which we individually purified by reverse phase chromatography or by hydrophobic interaction chromatography. Pseudexins A and B had relatively low specific toxicities in mice (i.p. LD50 of 1300 and 750 micrograms/kg, respectively), while C was non-toxic. All three had similar phospholipase A2 activities (43-53 muequiv H+ released/min/mg protein). The complete amino acid sequences of pseudexins A and B were determined. Amino acids were identical at 91 of the 117 residues. The first 28 residues of pseudexin C were determined, sufficient to show that C is structurally similar to A and B, but not identical with either. As judged by reactions with antisera against several other snake phospholipase A2 toxins, pseudexins A, B and C have very similar antigenic structures. We noted extensive homology with other phospholipases.
authors.affiliation: Department of Toxinology, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21701-5011.
authors.forename: J J
authors.initials: JJ
authors.lastname: Schmidt
authors.forename: J L
authors.initials: JL
authors.lastname: Middlebrook
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004546:Elapid Venoms / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay; D006868:Hydrolysis; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000032:analysis / Q000276:immunology; D010447:Peptide Hydrolases; D010740:Phospholipases / Q000302:isolation & purification*; D010741:Phospholipases A / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification*; D054467:Phospholipases A2; D011817:Rabbits
chemical_list: D004546:Elapid Venoms; D007527:Isoenzymes; D009498:Neurotoxins; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D010447:Peptide Hydrolases