Abstract
In this research a preliminary identification and biochemical and biological characterization of a PLA2 (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 PLA2s. Btae TX-I belongs to the Asp49 PLA2 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. PLA2 activity in presence of Mn2+, Mg2+, Cd2+ and Zn2+ was reduced either in presence or absence of Ca2+, suggesting that the arrangement of the catalytic site presents an exclusive structure for Ca2+. 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 PLA2 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 PLA2 from Bothriopsis taeniata is at the post-synaptic site.
Highlights
Phospholipase A2s (PLA2s, EC 3.1.1.4) represent a superfamily of lipolytic esterases that hydrolyze the sn-2 ester bond of phospholipids releasing free fatty acid and lysophospholipid
Btae TX-I was purified by two chromatographic steps, molecular exclusion chromatography followed by analytical chromatography reverse phase HPLC
The purification procedures of PLA2 Btae TX-I are summarized in Table 1 and this purified protein was selected for further biochemical and pharmacological characterization
Summary
Phospholipase A2s (PLA2s, EC 3.1.1.4) represent a superfamily of lipolytic esterases that hydrolyze the sn-2 ester bond of phospholipids releasing free fatty acid and lysophospholipid. At present with the discovery of additional PLA2s and based on amino acid sequences, 16 distinct groups of PLA2s were reported [2,3]. Secondary and tertiary structures and common catalytic properties, differences in the sequence of amino acids, confer to sPLA2 a wide spectrum of pharmacological effects. The venom of snakes may contain myotoxins that provoke important muscle necrosis at the snakebite site. These myotoxins include small myotoxic peptides that affect Na+ channels at the sarcolemma or sarcoplasmic reticulum, cardiotoxins or cytotoxic polypeptides present in the venom of elapid snakes and myotoxins with PLA2 activity or myotoxic PLA2 [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
