The amino acid sequence of bothropstoxin-II, an Asp-49 myotoxin from Bothrops jararacussu (Jararacucu) venom with low phospholipase A2 activity.
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.
Pereira
M F
MF
Department of Biochemistry, Institute of Biology, UNICAMP, Campinas-SP, Brazil.
Novello
J C
JC
Cintra
A C
AC
Giglio
J R
JR
Landucci
E T
ET
Oliveira
B
B
Marangoni
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001224:Aspartic Acid / Q000737:chemistry*; D017837:Bothrops; D002851:Chromatography, High Pressure Liquid; D003435:Crotalid Venoms / Q000737:chemistry* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D054501:Group II Phospholipases A2; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010741:Phospholipases A / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D054467:Phospholipases A2; D030162:Reptilian Proteins; D012697:Serine Endopeptidases / Q000378:metabolism
D003435:Crotalid Venoms; D030162:Reptilian Proteins; D001224:Aspartic Acid; D010741:Phospholipases A; D054501:Group II Phospholipases A2; D054467:Phospholipases A2; C072031:bothropstoxin II; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase