Biochemical Characterization of a PLA2 Btae TX-I Isolated from Bothriopsis taeniata Snake Venom: A Pharmacological and Morphological Study

Abstract

In this research a preliminary identification and biochemical and biological characterization of a PLA 2 (Btae TX-I) from the venom of a viperid snake, Bothriopsis taeniata (Speckled forest pit viper) were obtained. Btae TX-I was purified by two chromatographic steps, molecular exclusion chromatography followed by analytical chromatography reverse phase HPLC. Molecular mass behaved as a homogeneous single chain protein on SDS-PAGE, confirmed by MALDI-TOF spectrometry, indicating a molecular mass of 13889.98 Da. Tryptic peptides were determined in tandem mass spectrometry and showed similarity with other myotoxic PLA 2 s. Btae TX-I belongs to the Asp49 PLA 2 class, is enzymatically active in presence of a synthetic substrate and shows a minimum sigmoidal behavior, reaching its maximal activity at pH 8.0 and 35-45°C. PLA 2 activity in presence of Mn 2+ , Mg 2+ , Cd 2+ and Zn 2+ was reduced either in presence or absence of Ca 2+ , suggesting that the arrangement of the catalytic site presents an exclusive structure for Ca 2+ . Crotalic crotapotins from rattlesnake venom has significantly inhibited (p<0.05) the enzymatic activity of Btae TX-I. In ex vivo experiment, Btae TX-I caused partial blockade of the neuromuscular transmission in chick biventer cervicis preparations in a similar way to other Bothrops species. Btae TX-I also inhibited contractures in the upper concentration (50 µg) to exogenous KCl (20 mM). Histological analysis of the biventer cervicis incubated with Btae TX-I showed that just the highest Btae TX-I PLA 2 dose (50 µg) caused almost 27.4 ± 0.3% damaged fibers. The results give evidence that the main effect of type Asp49 Btae TX-I PLA 2 from Bothriopsis taeniata is at the post-synaptic site.

Clinical and Evolutionary Implications of Dynamic Coagulotoxicity Divergences in Bothrops (Lancehead Pit Viper) Venoms

“…This suggests that, at least in these venoms, the action may have a role in prey capture, with these snakes having reverted back to the ancestral fibrinogen-depleting anticoagulant condition. In addition, relative to procoagulant species, the arboreal species may have greater reliance upon the neurotoxic activity documented for those venoms [ 85 , 86 , 87 ] to subjugate prey. A lack of procoagulant activity might be beneficial in allowing neurotoxins to spread throughout the body, as localised clots might “trap” neurotoxins, preventing them from spreading.…”

Isolation and Characterization of a Myotoxic Fraction from Cerastes Vipera Snake Venom

“…The myotoxin CV-PL-F 4 has M.W of about 14,600. Phospholipases A 2 molecular mass range from 13 to 19 kDa [35] and typically requires Ca 2+ at for their catalytic activity [36]. PLA 2 isolated from snake venoms are much less lethal than neurotoxins [17,[37][38][39].…”