ISSN:
1573-4943
Keywords:
Bothropstoxin II
;
Bothrops jararacussu
;
myotoxin
;
phospholipase A2
;
amino acid sequence
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract 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 (M r = 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1022563401413
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