Researchers Priyanka Singh and Gurunathan Jayaraman have reported the heterologous expression and molecular characterization of a 15.3-kilodalton recombinant acidic phospholipase A2, designated NN-rPLA2, derived from Naja naja venom. Utilizing a prokaryotic expression system with the pGS21a vector, the investigators achieved a production yield of 101 milligrams per liter of the recombinant protein. The study, published in Molecular Biology Reports, assessed the recombinant enzyme across assays evaluating structural stability, enzymatic activity, hemolytic activity, antimicrobial activity, and cellular cytotoxicity.
Acidic phospholipase A2 enzymes from Naja naja venom are recognized for their enzymatic and antimicrobial potential, but scarce availability from native venom sources has historically constrained in-depth investigation and therapeutic evaluation. Heterologous expression in a bacterial host provides an alternative production route designed to overcome the harvest constraints associated with native snake venom, yielding sufficient material for structural and functional testing.
Structural evaluations demonstrated that NN-rPLA2 responds directly to calcium ions, with its alpha-helical content rising from 39.2 percent to 50 percent in the presence of 10 millimolar calcium chloride, accompanied by an increase in overall stability. At a concentration of 50 micrograms per microliter, the recombinant enzyme demonstrated functional stability across a pH range of 4 to 7 and maintained stability at temperatures ranging between 20 and 45 degrees Celsius.
Antimicrobial testing showed that the purified recombinant enzyme inhibited bacterial growth across multiple laboratory strains. NN-rPLA2 exhibited minimum inhibitory concentrations of 3.46 micrograms per milliliter against Escherichia coli, 11.70 micrograms per milliliter against Klebsiella pneumoniae, and 12.01 micrograms per milliliter against Bacillus cereus. In hemolytic evaluations, the enzyme produced a moderate hemolytic rate of 24.26 percent against human red blood cells.
In vitro cytotoxicity testing indicated selective cytotoxic activity between malignant and non-malignant cell models. NN-rPLA2 demonstrated a half-maximal inhibitory concentration of 11.302 micrograms per milliliter against MCF-7 breast cancer cells, compared to a significantly higher value of 30.898 micrograms per milliliter against non-cancerous MCF-10A cells. The authors concluded that these measured properties position NN-rPLA2 as a scalable recombinant candidate for subsequent antimicrobial and anticancer investigations.
Subject of Research: Heterologous expression and characterization of recombinant acidic phospholipase A2 from Naja naja venom
Article Title: Heterologous expression, molecular characterization, selective cytotoxicity and antimicrobial activity of acidic phospholipase A2 from Naja naja venom
Article References: Singh, P., & Jayaraman, G. (2026). Heterologous expression, molecular characterization, selective cytotoxicity and antimicrobial activity of acidic phospholipase A2 from Naja naja venom. Molecular Biology Reports, 53(1), Article 1921. https://doi.org/10.1007/s11033-026-12953-x
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DOI: 10.1007/s11033-026-12953-x
Keywords: Naja naja, phospholipase A2, recombinant protein, pGS21a vector, antimicrobial activity, cytotoxicity, MCF-7 cells, venom biochemistry, Heterologous, expression, molecular, characterization
