The amino acid sequence of bothropstoxin-II, an Asp-49 myotoxin from Bothrops jararacussu (Jararacucu) venom with low phospholipase A2 activity

• Published in: Journal of Protein Chemistry Vol. 17; no. 4; pp. 381 - 386
• Main Authors: Pereira, M F, Novello, J C, Cintra, A C, Giglio, J R, Landucci, E T, Oliveira, B, Marangoni, S
• Format: Journal Article
• Language: English
• Published: United States Springer Nature B.V 01-05-1998
• Subjects: Amino Acid Sequence; Amino acids; Animals; Aspartic Acid - chemistry; Bothrops; Bothrops jararacussu; Bothropstoxin; Calcium ions; Catalysis; Catalytic activity; Chromatography, High Pressure Liquid; Crotalid Venoms - chemistry; Crotalid Venoms - metabolism; Electrophoresis, Polyacrylamide Gel; Enzymatic activity; Enzymes; Group II Phospholipases A2; Homology; Hydrolysis; Lecithin; Methionine; Molecular biology; Molecular Sequence Data; Mutation; Myotoxins; Peptides; Phosphatidylcholine; Phospholipase; Phospholipase A2; Phospholipases A - chemistry; Phospholipases A - isolation & purification; Phospholipases A - metabolism; Phospholipases A2; Polypeptides; Reptilian Proteins; Residues; Serine Endopeptidases - metabolism; Venom; Yolk
• ISSN: 0277-8033; 1572-3887; 1573-4943
• DOI: 10.1023/A:1022563401413

The complete amino acid sequence of bothropstoxin-II (BthTX-II), a myotoxin isolated from Bothrops jararacussu snake venom, is reported. The results show that BthTX-II is an Asp-49 phospholipase A2 (PLA2)-like protein composed of a single polypeptide chain of 120 amino acid residues (Mr = 13,976), containing one methionine and 14 half-cystines. Despite a high degree of homology with other PLA2's and the presence of the strategic residues known to compose the Ca2+-binding loop, namely Tyr-28, Gly-30, Gly-32, and especially Asp-49, besides His-48, Tyr-52, and Asp-99, all of them directly or indirectly involved in catalysis, BthTX-II revealed a very low PLA2 activity when assayed on egg yolk phosphatidylcholine. We attribute this low catalytic activity to the existence of extra mutations, e.g., Trp-5 for Phe-5, which points to the need of considering other strategic positions, since only Lys-49 PLA2's have been considered to be devoid of this enzymatic activity.