title: Myotoxin II from Bothrops asper (Terciopelo) venom is a lysine-49 phospholipase A2.
abstract: A basic, dimeric myotoxic protein, myotoxin II, purified from Bothrops asper venom has a similar molecular weight and is immunologically cross-reactive with antibodies raised to previously isolated B. asper phospholipases A2, except that it shows only 0.1% of the phospholipase activity against L-alpha-phosphatidylcholine in the presence of Triton X-100. Its 121 amino acid sequence, determined by automated Edman degradation, clearly identifies it as a Lys-49 phospholipase A2. Key amino acid differences between myotoxin II and phospholipase active proteins in the Ca2(+)-binding loop region, include Lys for Asp-49, Asn for Tyr-28, and Leu for Gly-32. The latter substitution has not previously been seen in Lys-49 proteins. Other substitutions near the amino terminus (Leu for Phe-5 and Gln for several different amino acids at position 11) may prove useful for identifying other Lys-49 proteins in viperid and crotalid venoms. Myotoxin II shows greater sequence identity with other Lys-49 proteins from different snake venoms (Agkistrodon piscivorus piscivorus, Bothrops atrox, and Trimeresurus flavoviridis) than with another phospholipase A2 active Asp-49 molecule isolated from the same B. asper venom. This work demonstrates that phospholipase activity per se, is not required in phospholipase molecules for either myotoxicity or edema inducing activities.
authors.affiliation: Department of Molecular Biology, University of Wyoming, Laramie 82071.
authors.forename: B
authors.initials: B
authors.lastname: Francis
authors.forename: J M
authors.initials: JM
authors.lastname: Gutierrez
authors.forename: B
authors.initials: B
authors.lastname: Lomonte
authors.forename: I I
authors.initials: II
authors.lastname: Kaiser
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D002118:Calcium / Q000737:chemistry; D002417:Cattle; D003429:Cross Reactions; D003435:Crotalid Venoms / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D054501:Group II Phospholipases A2; D006801:Humans; D008239:Lysine / Q000737:chemistry; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D017830:Octoxynol; D010741:Phospholipases A / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D054467:Phospholipases A2; D011092:Polyethylene Glycols; D011487:Protein Conformation; D051381:Rats; D030162:Reptilian Proteins
chemical_list: D000906:Antibodies; D003435:Crotalid Venoms; D009498:Neurotoxins; D030162:Reptilian Proteins; D011092:Polyethylene Glycols; D017830:Octoxynol; D010741:Phospholipases A; D054501:Group II Phospholipases A2; D054467:Phospholipases A2; C061056:myotoxin II, Bothrops asper; D008239:Lysine; D002118:Calcium