Abstract
The microalgae Chlorella vulgaris represent a good model for the study of photosynthetic membranes and are rich in photosynthetic proteins, galactolipids, and pigments (Demarco et al., 2022). These photosynthetic organisms have been consumed in some parts of the world for centuries and their nutritional potential has been highlighted in many reports, explaining a growing interest in their use in new food applications (Torres-Tiji et al., 2020). However, their digestibility by gastrointestinal enzymes has not been extensively studied. So we used the Pancreatic lipase related-protein 2 (PLRP2) to get more information on the digestive mechanisms. Indeed, it has been shown to be responsible for the effective hydrolysis of galactolipids, the main lipids composing plant photosynthetic membranes. Guinea pig pancreatic lipase related-protein 2 (gPLRP2) is a model enzyme close to its human analogue, and that has been extensively studied for its ability to hydrolyze a wide range of acylglycerol substrates, exhibiting remarkable galactolipase and phospholipase A1 activity. In this study, Langmuir model monolayers were used to fellow the interfacial behavior of gPLRP2 at the level of natural plant lipid monolayers from Chlorella microalgae extracts, and to understand the impact of the chemical and physical heterogeneity of natural photosynthetic plant membranes on the enzymatic activity of gPLRP2. We compared also with data obtained on lipid extracts from nuts and almonds for which the composition is mainly composed of phospholipids. The results have shown that the enzymatic activity of gPLRP2 is with an optimum activity obtained at 15 mN/m. Interfacial studies showed enhanced adsorption of gPLRP2 onto natural monolayers containing negatively charged lipids, and that the compositional complexity in these systems induced a lag phase before the initiation of lipolysis, and a slowdown in enzymatic activity.