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

Arch Biochem Biophys. 2004 May 1;425(1):1-13. doi: 10.1016/j.abb.2004.02.007.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antivenins / pharmacology
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism*
  • Elapid Venoms / metabolism*
  • Elapidae / metabolism*
  • Erythrocytes / drug effects
  • Erythrocytes / metabolism
  • Isoenzymes / isolation & purification
  • Isoenzymes / metabolism
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Phospholipases A / drug effects
  • Phospholipases A / isolation & purification
  • Phospholipases A / metabolism*
  • Phospholipases A2
  • Phospholipids / metabolism
  • Substrate Specificity

Substances

  • Antivenins
  • Elapid Venoms
  • Isoenzymes
  • Phospholipids
  • Phospholipases A
  • Phospholipases A2