title: Adsorption of gastric lipase onto multicomponent model lipid monolayers with phase separation.
abstract: The enzymatic lipolysis of complex natural lipoproteic assemblies such as milk fat globules is central in neonatal digestion. This process first requires the rapid adsorption of a lipolytic enzyme, gastric lipase, onto the membrane enveloping the triglyceride substrate before the onset of catalytic activity. The interactions governing lipase adsorption onto this complex lipid/water interface are not fully elucidated. This study was designed to unravel the interactions of recombinant dog gastric lipase (rDGL) with model monolayers presenting liquid-liquid phase coexistence and mimicking the outer leaflet of the milk fat globule membrane. Combining biophysical tools (ellipsometry, tensiometry and atomic force microscopy), it was evidenced that rDGL partitions toward liquid expanded phase and at phase boundaries. rDGL gets adsorbed at several levels of insertion suggesting molecular cooperation that may favor insertion and strongly impacts on the lipid phase lateral organization. The addition of phosphatidylserine, negatively charged, reinforced adsorption; hence besides hydrophobic interactions and as further investigated through surface potential modeling, rDGL adsorption is favored by electrostatic interactions.
authors.affiliation: INRA-AGROCAMPUS, UMR 1253 STLO, France. Electronic address: claire.bourlieu@rennes.inra.fr.
authors.forename: Claire
authors.initials: C
authors.lastname: Bourlieu
authors.affiliation: IPR Institute of Physics, Rennes University 1, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Paboeuf
authors.affiliation: INRA-AGROCAMPUS, UMR 1253 STLO, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Chever
authors.affiliation: INRA-AGROCAMPUS, UMR 1253 STLO, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Pezennec
authors.affiliation: CNRS, Aix-Marseille University, UMR 7282 EIPL, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Cavalier
authors.affiliation: INRA-AGROCAMPUS, UMR 1253 STLO, France.
authors.forename: Fanny
authors.initials: F
authors.lastname: Guyomarc'h
authors.affiliation: INRA-AGROCAMPUS, UMR 1253 STLO, France.
authors.forename: Amélie
authors.initials: A
authors.lastname: Deglaire
authors.affiliation: INRA-AGROCAMPUS, UMR 1253 STLO, France.
authors.forename: Saïd
authors.initials: S
authors.lastname: Bouhallab
authors.affiliation: INRA-AGROCAMPUS, UMR 1253 STLO, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Dupont
authors.affiliation: CNRS, Aix-Marseille University, UMR 7282 EIPL, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Carrière
authors.affiliation: IPR Institute of Physics, Rennes University 1, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Vié
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000327:Adsorption; D000818:Animals; D002417:Cattle; D004285:Dogs; D006017:Glycolipids / Q000737:chemistry*; D006023:Glycoproteins / Q000737:chemistry*; D008049:Lipase / Q000737:chemistry*; D066292:Lipid Droplets; D018625:Microscopy, Atomic Force; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010718:Phosphatidylserines / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D055672:Static Electricity; D013270:Stomach / Q000737:chemistry / Q000201:enzymology; D013500:Surface Tension; D053835:Unilamellar Liposomes / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D006017:Glycolipids; D006023:Glycoproteins; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D011994:Recombinant Proteins; D053835:Unilamellar Liposomes; C110367:milk fat globule; D014867:Water; C094877:dioleoyl phosphatidylethanolamine; D015060:1,2-Dipalmitoylphosphatidylcholine; C042511:1,2-dioleoylphosphatidylserine; D008049:Lipase; C017251:1,2-oleoylphosphatidylcholine
keywords: Atomic force microscopy; Digestive lipase; Liquid phase coexistence; Milk fat globule; Model lipid monolayer