title: Differential hydrolysis of erythrocyte and mitochondrial membrane phospholipids by two phospholipase A2 isoenzymes (NK-PLA2-I and NK-PLA2-II) from the venom of the Indian monocled cobra Naja kaouthia.
abstract: We previously demonstrated that venom from the Indian monocled cobra Naja kaouthia is a rich source of phospholipase A2 enzymes, and we purified and characterized a major PLA2 isoenzyme (NK-PLA2-I) from N. kaouthia venom. In the present study, we report the purification and biochemical characterization of a second PLA2 isoenzyme (NK-PLA2-II) from the same venom. A comparison of the membrane phospholipid hydrolysis patterns by these two PLA2s has revealed that they cause significantly more damage to mitochondrial membranes (NK-PLA2-I > NK-PLA2-II) as compared to erythrocyte membranes due to more efficient binding of the enzymes to mitochondrial membranes. Fatty acid release patterns by these PLA2s from the membrane phospholipid PC-pools indicate that NK-PLA2-I does not discriminate between saturated and unsaturated fatty acids whereas NK-PLA2-II shows a preference for unsaturated fatty acids during the initial phase of attack. The current investigation provides new insight into the molecular arrangement of NK-PLA2-sensitive domains in erythrocyte and mitochondrial membranes and highlights the contribution of polar, but uncharged, amino acids such as serine and cysteine in NK-PLA2 induced membrane damage.
authors.affiliation: Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur 784 028, India.
authors.forename: Robin
authors.initials: R
authors.lastname: Doley
authors.forename: Glenn F
authors.initials: GF
authors.lastname: King
authors.forename: Ashis K
authors.initials: AK
authors.lastname: Mukherjee
mesh_terms: D000818:Animals; D000997:Antivenins / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D004546:Elapid Venoms / Q000378:metabolism*; D017815:Elapidae / Q000378:metabolism*; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010741:Phospholipases A / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D054467:Phospholipases A2; D010743:Phospholipids / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D000997:Antivenins; D004546:Elapid Venoms; D007527:Isoenzymes; D010743:Phospholipids; D010741:Phospholipases A; D054467:Phospholipases A2