Interaction of trypsin with multilamellar vesicles of soybean lipids

The pH dependence of complex formation of trypsin with multilamellar vesicl es (MLV) of soybean lipids has been investigated. The lipids were character ized by the same phospholipid composition, but the content of other lipids differed. Decrease of pH or introduction of negatively charged components i nto the lipid samples increased trypsin content in the protein-lipid comple xes. This suggests electrostatic interaction between the protein and soybea n lipids. The dependence of trypsin activity in the complexes with MLV on t heir concentration and on the presence of an ionic detergent was studied. T rypsin-MLV interaction did not result in complete inactivation of the prote in molecules. Moreover, the effects of dilution and addition of ionic deter gent on trypsin activity were additive. Using a fluorescence technique, com plex formation with MLV was found to stabilize trypsin molecules, preventin g their autolysis.