[Spin-labeling studies on interaction of phospholipase A2 from cobra poison with phospholipid membranes]

Phospholipase A2 interactions with phospholipid liposomes and vesicles were studied by using unhydrolysed spin-labeling 2-alkyl phosphatidylcholine. These interactions have polar nature. Phospholipase A2 hydrolyses only the neighbouring phospholipid monolayer. The hydrophobic layer of liposomes is not permeable for the enzyme. Phospholipase A2 are attached to lysophosphatidylcholine after hydrolysis and it stabilizes the structure of vesicles. The stabilizing effect of the enzyme makes the vesicles unpermeable for Na+, Cl-ions and protons. Moreover, the phospholipase A2 prevents the phospholipid exchange between the vesicles and their fusion.