Abstract
A new PLA2 (Bp-13) was purified from Bothrops pauloensis snake venom after a single chromatographic step of RP-HPLC on μ-Bondapak C-18. Amino acid analysis showed a high content of hydrophobic and basic amino acids and 14 half-cysteine residues. The N-terminal sequence showed a high degree of homology with basic Asp49 PLA2 myotoxins from other Bothrops venoms. Bp-13 showed allosteric enzymatic behavior and maximal activity at pH 8.1, 36°–45°C. Full Bp-13 PLA2 activity required Ca2+; its PLA2 activity was inhibited by Mg2+, Mn2+, Sr2+, and Cd2+ in the presence and absence of 1 mM Ca2+. In the mouse phrenic nerve-diaphragm (PND) preparation, the time for 50% paralysis was concentration-dependent (P < 0.05). Both the replacement of Ca2+ by Sr2+ and temperature lowering (24°C) inhibited the Bp-13 PLA2-induced twitch-tension blockade. Bp-13 PLA2 inhibited the contractile response to direct electrical stimulation in curarized mouse PND preparation corroborating its contracture effect. In biventer cervicis preparations, Bp-13 induced irreversible twitch-tension blockade and the KCl evoked contracture was partially, but significantly, inhibited (P > 0.05). The main effect of this new Asp49 PLA2 of Bothrops pauloensis venom is on muscle fiber sarcolemma, with avian preparation being less responsive than rodent preparation. The study enhances biochemical and pharmacological characterization of B. pauloensis venom.
Highlights
Phospholipase A2 belongs to an expanding superfamily of enzymes that catalyzes ester bond hydrolysis at the sn-2 position of 1,2-diacyl-sn-3-phosphoglycerides and generates arachidonic acid
We describe the isolation and Biochemistry Research International enzymatic characterization of a highly basic PLA2 from the venom of B. pauloensis
The Bp-13, which was eluted at 39 min, was characterized as a not yet described PLA2-active toxin (Figure 2(a))
Summary
Phospholipase A2 belongs to an expanding superfamily of enzymes that catalyzes ester bond hydrolysis at the sn-2 position of 1,2-diacyl-sn-3-phosphoglycerides and generates arachidonic acid. Despite the variety of the local and systemic pathophysiological effect, such as myotoxicity, neurotoxicity, anticoagulation, hemolysis, hypotension, platelet aggregation inhibition, and bactericidal and proinflammatory activities, PLA2 groups show highly conserved molecular regions and similar three-dimensional structure [3]. The majority of such local and systemic effects caused by Bothrops sp. Generally the neurotoxic effects are unnoticed clinically, they can be observed during in vitro experiments and are frequently associated with PLA2 of bothropic venoms [6,7,8,9,10,11,12,13,14]. We investigated whether this isolated PLA2 possesses neurotoxic activity
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