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.