Isolation and Characterization of A2-EPTX-Nsm1a, a Secretory Phospholipase A 2 from Malaysian Spitting Cobra ( Naja sumatrana ) Venom.

Phospholipase A 2 (PLA 2 ) toxins are one of the main toxin families found in snake venom. PLA 2 toxins are associated with various detrimental effects, including neurotoxicity, myotoxicity, hemostatic disturbances, nephrotoxicity, edema, and inflammation. Although Naja sumatrana venom contains substantial quantities of PLA 2 components , there is limited information on the function and activities of PLA 2 toxins from the venom. In this study, a secretory PLA 2 from the venom of Malaysian N. sumatrana , subsequently named A2-EPTX-Nsm1a, was isolated, purified, and characterized. A2-EPTX-Nsm1a was purified using a mass spectrometry-guided approach and multiple chromatography steps. Based on LC-MSMS, A2-EPTX-Nsm1a was found to show high sequence similarity with PLA 2 from venoms of other Naja species. The PLA 2 activity of A2-EPTX-Nsm1 was inhibited by 4-BPB and EDTA. A2-EPTX-Nsm1a was significantly less cytotoxic in a neuroblastoma cell line (SH-SY5Y) compared to crude venom and did not show a concentration-dependent cytotoxic activity. To our knowledge, this is the first study that characterizes and investigates the cytotoxicity of an Asp49 PLA 2 isolated from Malaysian N. sumatrana venom in a human neuroblastoma cell line.