Exploring the structural and functional aspects of the phospholipase A2 from Naja spp.

Naja spp. venom is a natural source of active compounds with therapeutic application potential. Phospholipase A₂ (PLA₂) is abundant in the venom of Naja spp. and can perform neurotoxicity, cytotoxicity, cardiotoxicity, and hematological disorders. The PLA₂s from Naja spp. venoms are Asp 49 isoenzymes with the exception of PLA₂ Cys 49 from Naja sagittifera. When looking at the functional aspects, the neurotoxicity occurs by PLA₂ called β-toxins that have affinity for phosphatidylcholine in nerve endings and synaptosomes membranes, and by α-toxins that block the nicotinic acetylcholine receptors in the neuromuscular junctions. In addition, these neurotoxins may inhibit K⁺ and Ca⁺⁺ channels or even interfere with the Na⁺/K⁺/ATPase enzyme. The disturbance in the membrane fluidity also results in inhibition of the release of acetylcholine. The PLA₂ can act as anticoagulants or procoagulant. The cytotoxicity exerted by PLA₂s result from changes in the cardiomyocyte membranes, triggering cardiac failure and hemolysis. The antibacterial activity, however, is the result of alterations that decrease the stability of the lipid bilayer. Thus, the understanding of the structural and functional aspects of PLA₂s can contribute to studies on the toxic and therapeutic mechanisms involved in the envenomation by Naja spp. and in the treatment of pathologies.