Purification and inhibitory profile of phospholipase A2 inhibitors from Australian elapid sera

Abstract

Although the resistance of snakes to their own venom is well known, until now no investigators have examined the serum of Australian snakes. Here we describe the identification and purification of a range of phospholipase A2 (PLA2) inhibitors from the serum of Australian elapids. All PLA2 inhibitors were composed of two protein chains, an α-chain and a β-chain. The α-chains were approx. 22.5 kDa in size and variably glycosylated, whereas the β-chains were approx. 19.8 kDa in size and not glycosylated. Identification of isoforms of the two subunit chains was significant because three of the six sera examined were from single snake specimens. In addition, the glycosylation patterns of the α-chains were thoroughly investigated in these unpooled sera. The functional and structural properties of the purified inhibitors were studied. Uniquely, a snake PLA2 inhibitor was found to inhibit human type II PLA2 enzyme, which has implications for the treatment of the many diseases in which PLA2 enzymes have been implicated. Further, we demonstrate that the inhibitor forms a non-covalent association with a purified PLA2 enzyme. Finally, the purified PLA2 inhibitor was shown to protect in vivo against the lethal affects of a homologous PLA2 enzyme, suggesting a role for PLA2 inhibitors in the treatment of snake bite victims.

Alpha-type phospholipase A2 inhibitors from snake blood

“…Their amino acid sequences contain two sets of standards cysteine residues, responsible for the formation of the three-finger motif [51]. This type of inhibitor has been reported in different snakes, as Crotalus durissus terrificus [52–54], Naja naja kaouthia [55, 56], Agkistrodon blomhoffii siniticus [57], Trimeresurus flavoviridis [58], Laticauda semifasciata [59], Elaphe quadrivirgata [60] , E. climacophora [50], Cerrophidion godmani [32], Notechis ater , Notechis ater serventyi [61], Oxyuranus scutellatus and O. microlepidotus [61], Pseudonaja textilis [61], Python reticulates [62], Notechis scutatus [63], Lachesis muta muta [64], Protobothrops flavoviridis [65], Bothrops alternatus, B. erythromelas, B. jararaca, B. moojeni, B. neuwiedi [51], Bothrops jararacussu [39] and Crotalus durissus collilineatus [66] and these γPLIs appear to be less specific, since they inhibit PLA 2 from groups I, II and III.…”

Endogenous phospholipase A2 inhibitors in snakes: a brief overview

“…The actual contribution of the secondary subunits B to the full functionality of the sbγPLI-IIs, whenever applicable, remains to be clarified. It has been speculated that the subunit B might play a structural rather than a functional role in the sbγPLIs from Australian elapid species [42]. On the other hand, an ancestral role has been suggested for the subunit B compared to subunit A, in the sbγPLI from the Asian P. flavoviridis [43].…”

Resistance Is Not Futile: Widespread Convergent Evolution of Resistance to Alpha-Neurotoxic Snake Venoms in Caecilians (Amphibia: Gymnophiona)

“…to act against the venom of snake prey [31]; the Boa Constrictor (Boa constrictor) to escape coral snake (Micrurus spp.) predators [32]; the Indigo Snake (Drymarchon couperi) to act against pit viper prey's venom [33]; and in many venomous snakes against their own toxins [34,35]. Modifications of the target itself include von Willebrand factor (VWF) in opossums, which acts against the venoms of pit viper prey and predators [36].…”