AGGREGATATION, FUSION AND AQUEOUS CONTENT RELEASE FROM LIPOSOMES INDUCED BY LYSOZYME DERIVATIVES - EFFECT ON THE LYTIC ACTIVITY

Chemically modified lysozymes, namely: N-succinyl lysozyme, glycine me thyl ester of N-succinyl lysozyme and oxoindole lysozyme have been pre pared, Aggregation, fusion and leakage of phospholipid vesicles induce d by these derivatives have been studied in comparison with the effect of the unmodified protein, The experiments were carried out with nega tively charges 9PC/PA, 9:1) and uncharged (PC and PC/DOPE/Chol (10:5:5 )) lipid vesicles of different packing. Fusion and aggregation of nega tively charged phospholipid vesicles is induced by proteins positively charged at pH 7.0 involving electrostatic interactions. a similar pat tern on fusion and aggregation of the least stably packed lipid vesicl es points also to hydrophobic forces playing a role in the lipid-prote in interaction. A conformational change of the protein involved increa sing beta-turns, loops and unordered structure at the expenses of beta -sheet without affecting alpha helix content. The conformational effec t is necessary to provoke the effects studied, since one of the deriva tives (N-succinyl lysozyme) neither changes conformation nor causes ag gregation and fusion of vesicles, However, there is no relationship be tween lysozyme activity and fusion or aggregation of lipid vesicles th at catalytic and fusogenci sites of, indicating lysozyme are topograph ically different.