KINETICS OF SPREADING OF DOPC LIPOSOMES AT THE AIR-WATER-INTERFACE SUBJECTED TO PHOSPHOLIPASE A(2) HYDROLISIS

The kinetics of surface film formation from DOPC small unilamellar liposomes spread at the air-water interface was studied by recording the surface pressure and the surface potential. The rate constants of the surface transformation of perfectly closed vesicles into open surface active structures was determined. It was found that the surface transformation was accelerated by enzymatic hydrolysis. A theoretical approach, describing the coupling of the surface transformation with the catalytic hydrolysis in the scooting mode of bilayered liposomes is developed. Values of the specific activity of hydrolysis of DOPC bilayered vesicles by phospholipase A, from Vipera berus orientalis were obtained by this method and compared with those previously obtained by the classical pH-stat titration method.