Non-covalent interaction of phospholipase A2 (PLA2) and kaouthiotoxin (KTX) from venom of Naja kaouthia exhibits marked synergism to potentiate their cytotoxicity on target cells

Research Report

J Venom Res (2010), Vol 1, 37-42

Published online: 30 September 2010

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Ashish K Mukherjee*

Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur-784 028, Assam, India

*Correspondence to: Ashis K Mukherjee, Email:, Tel: +91 9957 184351, Fax: +91 3712 267006

Received: 26 July 2010, Revised: 07 September 2010, Accepted: 09 September 2010

© Copyright The Authors


Present study shows that non-covalent interaction of kaouthiotoxin (KTX) with their respective pohospholipase A 2 (PLA 2)from the venom of N. kaouthia displayed marked synergism to exert cytotoxicity without altering the biochemical properties of PLA 2. For example, although NK-PLA 2 or KTX alone did not induce appreciable hemolysis of washed human erythrocytes; however, the hemolytic potency of NK-PLA 2: KTX complex was significantly higher. Identically, selective lysis of virus infected Sf9 and normal Tn insect cells was further enhanced by the cognate NK-PLA 2: KTX complex as compared to individual components of the complex. Gas-chromatographic analysis of fatty acids released from intact erythrocytes by cytotoxic action of individual NK-PLA 2 and NK-PLA 2: KTX complex demonstrated that ratio between saturated fatty acids (SFA) and unsaturated FA (UFA) was increasing with time of hydrolysis of RBC either in the case of NK-PLA 2 or NK-PLA 2-KTX complex suggesting NK-PLA 2-KTX complex apparently displayed the more preference for glycerophospholipids with SFAs on the sn-2 position. Therefore, it may be suggested that KTX first destabilize the target cell membrane followed by higher enzymatic activity of PLA 2 on dislocated and disorganized phospholipid bilayers resulting in a significantly higher (p < 0.05) membrane damage by NK-PLA 2-KTX complex compared to individual components of the complex.

KEYWORDS: Cytotoxicity, cobra venom, kaouthiotoxins, Naja kaouthia, phospholipase A 2, protein-protein interaction