title: A possible orientation change of cardiotoxin molecule during its interaction with phospholipid monolayer.
abstract: The monomolecular film technique was used in order to study the specific interactions of 4 cardiotoxins from Elapidae snake venom Naja mossambica mosambica with different phospholipids. The interaction, at pH 7.5, of cardiotoxin (10(-7) M) with both neutral and negatively charged phospholipids occurs up to a very high critical surface pressure (pi = 45 dynes/cm with the latest). The apparent molecular area of cardiotoxin molecule, during its insertion into a negatively charged phospholipid film, presents only two characteristic values: 1400 A2 for pi less than 20 dynes/cm and 420 A2 for pi greater than 30 dynes/cm, the transition occurring in a very narrow range of surface pressure (25 +/- 5 dynes/cm). Thus, according to the surface pressure, the cardiotoxin may present two different orientations: "flat" or "edgewise" and the transition between both could account for lytic activity of cardiotoxin.
mesh_terms: D004179:Cobra Cardiotoxin Proteins; D004546:Elapid Venoms; D006863:Hydrogen-Ion Concentration; D010743:Phospholipids; D011312:Pressure; D011487:Protein Conformation; D013499:Surface Properties
chemical_list: D004179:Cobra Cardiotoxin Proteins; D004546:Elapid Venoms; D010743:Phospholipids