What are the mechanisms of gastrointestinal lipases adsorption onto heterogenous biomimetic vegetal membranes?

International audience ; Gastrointestinal lipases are crucial for lipid hydrolysis and must get adsorbed onto the substrate interface prior lipolysis. Such adsorption had not been deeply investigated on biomimetic vegetal membranes. Our objective was thus to characterize such adsorption and lipolysis using complementary biophysical tools (tensiometry, ellipsometry, atomic force microscopy) and in vitro digestion.Heterogenous monolayers based on galactolipids, phospholipids, and phytosterols were used. Four lipases were studied: i) gastric lipase (GL), ii) pancreatic lipase 2 (PLRP2), (iii) pancreatic triacylglycerol lipase and its cofactor, colipase (PTL/coPTL), and (iv) pancreatic secreted phospholipase A2 (sPLA2-IB).A strong surfactant property of GL and its preferential adsorption onto expanded lipid phase and at the phase boundary were observed, in line with previous results on milk fat globule membrane. With PLRP2, changes in surface pressure indicated a lipolytic activity. Such variation was not observed upon PTL/coPTL adsorption, and may be related to the absence of activity of PTL on polar lipids. The injection of sPLA2-IB did not indicate a clear trend of lipolysis on the lipid film but changed the morphology of condensed domains.This study is a step forward to understand the interactions of gastrointestinal lipases with plant lipid membranes, an overlooked aspect of lipid digestion