Structural and functional characterization of brazilitoxins II and III (BbTX-II and -III), two myotoxins from the venom of Bothrops brazili snake.
We report the purification and biochemical/pharmacological characterization of two myotoxic PLA(2) (BbTX-II K49 PLA(2) homologue and BbTX-III PLA(2)) from Bothrops brazili venom. Both were purified by a single chromatographic step on reverse phase HPLC, showing M(r) approximately 14 kDa for both myotoxins, showing high content of hydrophobic and basic amino acids as well as 14 half-cysteine residues. The BbTX-II K49 PLA(2) homologue and BbTX-III PLA(2), had a sequence of 121 amino acid residues. BbTX-II: [amino acid sequence: see text] with pI value 8.73. BbTX-III: [amino acid sequence: see text] with a pI value of 8.46. BbTX-III presented PLA(2) activity in the presence of a synthetic substrate and showed a minimum sigmoidal behavior, reaching its maximal activity at pH 8.0 and 35-45 degrees C. Maximum PLA(2) activity required Ca(2+). In vitro, BbTX-II K49 PLA(2) homologue and BbTX-III PLA(2) caused a blockade of the neuromuscular transmission in young chick biventer cervicis preparations in a similar way to other Bothrops species. In mice, BbTX-II K49 PLA(2) homologue and BbTX-III PLA(2) induces myonecrosis and edema-forming activity. All these biological effects induced by the BbTX-II K49 PLA(2) homologue, occur in the absence of a measurable PLA(2) activity in vitro, further supporting the concept of catalytic independent mechanisms exerted by Lys49 proteins.
Huancahuire-Vega
Salomón
S
Department of Biochemistry, Institute of Biology, State University of Campinas, Campinas, SP, Brazil.
Ponce-Soto
Luis Alberto
LA
Martins-de-Souza
Daniel
D
Marangoni
Sergio
S
D000595:Amino Acid Sequence; D000818:Animals; D017837:Bothrops; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D003435:Crotalid Venoms / Q000737:chemistry* / Q000494:pharmacology / Q000633:toxicity; D004591:Electrophoresis, Polyacrylamide Gel; D051379:Mice; D008969:Molecular Sequence Data; D054467:Phospholipases A2 / Q000737:chemistry* / Q000494:pharmacology* / Q000633:toxicity*; D011487:Protein Conformation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D003435:Crotalid Venoms; D054467:Phospholipases A2; C545667:brazilitoxin II, Bothrops brazili; C545668:brazilitoxin III, Bothrops brazili