RAYAPATI, ANANDA MURALIVEMULAPATI, BHADRAMURTHYCHANDA, CHANDRASEKHAR2024-11-302024-11-302024-03RAYAPATI ANANDA MURALI, VEMULAPATI BHADRAMURTHY, CHANDA CHANDRASEKHAR. Cobra (Naja naja) venom L-amino acid oxidase (NNLAAO70) induces apoptosis and secondary necrosis in human lung epithelial cancer cells. Journal of Biosciences. 2024 Mar; 49: 1-110250-59910973-7138https://imsear.searo.who.int/handle/123456789/237963Snake venom L-amino acid oxidases (LAAOs) are flavoenzymes with diverse physiological and pharmacological effects. These enzymes are found to showcase anticoagulant, antiplatelet, cytotoxicity and other biological effects in bite victims. However, the exact mechanism through which they exhibit several biological properties is not yet fully understood. The current study focussed on the purification of cobra venom LAAO and the functional characterization of purified LAAO. A novel L-amino acid oxidase NNLAAO70 with a molecular weight ~70 kDa was purified from the venom of an Indian spectacled cobra (Naja naja). NNLAAO70 showed high substrate specificity for L-His, L-Leu, and L-Arg during its LAAO activity. It inhibited adenosine di-phosphate (ADP) and collagen-induced platelet aggregation process in a dose-dependent manner. About 60% inhibition of collagen-induced and 40% inhibition of ADP-induced platelet aggregation was observed with a 40 ?g/ml dose of NNLAAO70. NNLAAO70 exhibited bactericidal activity on Bacillus subtilis, Escherichia coli, Bacillus megaterium, and Pseudomonas fluorescens. NNLAAO70 also showed cytotoxicity on A549 cells in vitro. It showed severe bactericidal activity on P. fluorescens and lysed 55% of cells. NNLAAO70 also exhibited drastic cytotoxicity on A549 cells. At 1 ?g/ml dosage, it demonstrated a 60% reduction in A549 viability and induced apoptosis upon 24-h incubation. H2O2 released during oxidative deamination reactions played a major role in NNLAAO70-induced cytotoxicity. NNLAAO70 significantly increased intracellular reactive oxygen species (ROS) levels in A549 cells by six fold when compared to untreated cells. Oxidative stress-mediated cell injury is the primary cause of NNLAAO70-induced apoptosis in A549 cells and prolonged oxidative stress caused DNA fragmentation and activated cellular secondary necrosis.ApoptosisIndian spectacled cobraL-amino acid oxidaseoxidative stressplatelet aggregation inhibitionsecondary necrosisJournal ArticleIndiaDepartment of Biotechnology, Koneru Lakshmaiah Education Foundation, Vaddeswaram, Guntur 522 502, IndiaDepartment of Biotechnology, Koneru Lakshmaiah Education Foundation, Vaddeswaram, Guntur 522 502, India; Cool Climate Oenology and Viticulture Institute, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1, CanadaDepartment of Biotechnology, Koneru Lakshmaiah Education Foundation, Vaddeswaram, Guntur 522 502, India