Synergistically acting PLA2: Peptide hemorrhagic complex from Daboia russelii venom

Abstract

Snake venoms are complex mixture of enzymatic and non-enzymatic proteins. Non-covalent protein–protein interaction leads to protein complexes, which bring about enhanced pharmacological injuries by their synergistic action. Here we report identification and characterization of a new Daboia russelii hemorrhagic complex I (DR–HC-I) containing phospholipase A2 (PLA2) and non-enzymatic peptide. DR–HC-I was isolated from the venom of D. russelii by CM-Shepadex-C25 and gel permeation chromatography. Individual components were purified and identified by RP-HPL chromatography, mass spectrometry and N-terminal amino acid sequencing. DR–HC-I complex was lethal to mice with the LD50 dose of 0.7 mg/kg body weight with hemorrhagic and neurotoxic properties. DR–HC-I complex consists of non-hemorrhagic PLA2 and neurotoxic non-enzymatic peptide. The non-enzymatic peptide quenched the intrinsic fluorescence of PLA2 in a dose dependent manner, signifying the synergistic interaction between two proteins. PLA2 and peptide toxin in a 5:2 M ratio induced skin hemorrhage in mice with MHD 20 μg. However, addition of ANS (1-Anilino-8-naphthalene sulfonate) to DR–HC–I complex inhibited skin hemorrhagic effect and also synergic interaction. But there was no impact on PLA2 due to this synergistic interaction, and indirect hemolytic or plasma re-calcification activity. However, the synergistic interaction of PLA2 and non-enzymatic peptide contributes to the enhanced venom-induced hemorrhage and toxicity of Daboia russellii venom.