A novel pentameric phospholipase A2 myotoxin (PophPLA2) from the venom of the pit viper Porthidium ophryomegas
2018
Vindas, Julio | Carrera, Yarina | Lomonte, Bruno | Gutíerrez, José María | Calvete, Juan J. | Sanz, Libia | Fernández, Julián
The first toxin isolated from the venomous pit viper Porthidium ophryomegas is a basic pentameric phospholipase A₂ (PophPLA₂). Elucidation of its amino acid sequence showed that it belongs to the group IIA of secreted PLA₂s, with the presence of all 14 conserved cysteine positions. The toxin displayed catalytic activity, in agreement with the presence of Asp49 in its sequence of 121 residues. SDS-PAGE analysis revealed that this toxin is pentameric in non-reducing conditions, a structural organization that has not been described for any viperid PLA₂. PophPLA₂ displayed moderate myotoxic (in vivo) and cytotoxic (in vitro) activities, as well as anticoagulant activity on human plasma (in vitro). PophPLA₂ was not lethal, and did not induce signs of toxicity or distress in mice, when administered intravenously at a dose of up to 100 μg (5.9 μg/g). The toxin showed highest sequence identity with other PLA₂s from the venoms of ancestral Asian pit viper species.
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