Modulation of gastric lipase adsorption onto mixed galactolipid-phospholipid films by addition of phytosterols

The rapid and preferential adsorption of a gastric lipase recombinant dog gastric lipase (rDGL) in heterogeneous films of phospholipids and triacylglycerols has previously been unveiled using Langmuir films analyzed by tensiometry, ellipsometry and Langmuir-Blodgett transfer coupled to atomic force microscopy. Here we invest the adsorption behavior of rDGL in heterogeneous galactolipid and mixed galactolipid-phospholipid or galactolipid-phospholipid-phytosterol films representative of plant membrane. Again rDGL, preferentially got adsorbed at the expanded lipid phases of the films underlining the genericity of such adsorption behavior. The addition of phytosterols to these mixtures resulted in the creation of defects, favoring the adsorption of rDGL at the fluid phases, but also improving the adsorption capacities of the lipase at the phase boundaries and towards the defects in the condensed phase. rDGL, like all gastric lipases, does not show any activity on galactolipids and phospholipids but its adsorption impacts their lateral organization and may change the adsorption and activity of other lipolytic enzymes in the course of digestion. [Display omitted] •rDGL binds to the fluid phase of homogeneous galactolipid monolayer.•The orientation of galactolipid polar heads limits the adsorption capacity of rDGL.•rDGL was excluded from condensed phase domains in mixed heterogenous galactolipid-phospholipid monolayer.•Defects created in the condensed phase by addition of phytosterol favor rDGL adsorption.