Aqueous two-phase systems : a simple methodology to obtain mixtures enriched in main toxins of Bothrops alternatus venom
Fecha
2016Autor
Gómez, Gabriela Noemí
Leiva, Laura Cristina
Nerli, Bibiana Beatriz
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Phospholipase A2 (PLA2) and protease (P) are enzymes responsible of myotoxic, edematogenic and hemostasis
disorder effects observed in the envenomation by Bothrops alternatus pitviper. Their partitioning
coefficient (Kp) in different polyethyleneglycol/potassium phosphate aqueous two-phase systems
(ATPSs) was determined in order to both achieve a better understanding of the partitioning mechanism
and define optimal conditions for toxin isolation. Polyethyleneglycols (PEGs) of molecular weights 1000;
3350; 6000 and 8000; different temperatures (5, 20 and 37 C) and phase volume ratios of 0.5; 1 and 2
were assayed. PLA2 partitioned preferentially to the top phase while P mainly distributed to the bottom
phase. Either entropically- or enthalpically-driven mechanisms were involved in each case (PLA2 and P).
The aqueous two-phase system formed by PEG of MW 3350 (12.20% wt/wt) and KPi pH 7.0 (11.82% wt/
wt) with a volume ratio of one and a load of 1.25 mg of venom/g of system showed to be the most
efficient to recover both enzymes. It allowed obtaining the 72% of PLA2 in the top phase with a purification
factor of 2 and the 82% of P at the bottom phase simultaneously. A further adsorption batch step
with DEAE-cellulose was used to remove satisfactorily the PEG from the top phase and recover the active
PLA2.
The proposed methodology is simple, inexpensive, and only requires professionals trained in handling
basic laboratory equipment. It could be easily adoptable by developing countries in which the snakebite
accidents cause considerable morbidity and mortality.
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