| dc.description.abstract | We describe the interaction of various phospholipases A2 (PLA2) from snake venoms of the family Viperidae
(Macrovipera lebetina obtusa, Vipera ursinii renardi, Bothrops asper) with giant unilamellar vesicles (GUVs)
composed of natural brain phospholipids mixture, visualized through fluorescence microscopy. The membrane
fluorescent probes 8-anilino-1-naphthalenesulfonicacid (ANS), LAUDRAN and PRODAN were used to assess
the state of the membrane and specifically mark the lipid packing and membrane fluidity. Our results have
shown that the three PLA2s which contain either of aspartic acid, serine, or lysine residues at position 49 in the
catalytic center, have different effects on the vesicles. The PLA2 with aspartic acid at this position causes the
oval deformation of the vesicles, while serine and lysine-containing enzymes lead to an appreciable increase of
fluorescence intensity in the vesicles membrane, wherein the shape and dimensions of GUVs have not changed,
but in this case GUV aggregation occurs. LAURDAN and PRODAN detect the extent of water penetration into the
bilayer surface. We calculated generalized polarization function (GP), showing that for all cases (D49 PLA2, S49
PLA2 and K49 PLA2) both LAUDRAN and PRODAN GP values decrease. A higher LAURDAN GP is indicative of
low water penetration in the lipid bilayer in case of K49 PLA2 compared with D49 PLA2, whereas the PRODAN
mainly gives information when lipid is in liquid crystalline phase. | |
