title: New insights into the pH-dependent interfacial adsorption of dog gastric lipase using the monolayer technique.
abstract: The access to kinetic parameters of lipolytic enzyme adsorption onto lipids is essential for a better understanding of interfacial enzymology and lipase-lipid interactions. The interfacial adsorption of dog gastric lipase (DGL) was monitored as a function of pH and surface pressure (Π), independently from the catalytic activity, using non-hydrolysable 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) monomolecular films. The acid-stable DGL, which initiates fat digestion in the stomach, was then selected because its adsorption kinetics onto hydrophobic solid surfaces were already studied. This gastric lipase was therefore used as a model enzyme to validate both experimental and theoretical approaches. Results show that the adsorption process of DGL at the lipid/water interface depends on a pH-dependent adsorption equilibrium coefficient which is optimum at pH 5.0 (K(Ads) = 1.7 ± 0.05 × 10(8)M(-1)). KAds values further allowed an indirect estimation of the molar fraction (ΦE*(%), mol%) as well as the molecular area (AE*) of DGL adsorbed onto DLPC monolayer. Based on these data, a model for DGL adsorption onto DLPC monolayer at pH 5.0 is proposed for a surface pressure range of 15-25 mNm(-1).
authors.affiliation: CNRS, Aix-Marseille Université, Enzymologie Interfaciale et Physiologie de la Lipolyse, UMR 7282, 31 chemin Joseph Aiguier, 13402 Marseille cedex 20, France.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Bénarouche
authors.affiliation: CNRS, Aix-Marseille Université, Enzymologie Interfaciale et Physiologie de la Lipolyse, UMR 7282, 31 chemin Joseph Aiguier, 13402 Marseille cedex 20, France.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Point
authors.affiliation: CNRS, Aix-Marseille Université, Enzymologie Interfaciale et Physiologie de la Lipolyse, UMR 7282, 31 chemin Joseph Aiguier, 13402 Marseille cedex 20, France.
authors.forename: Goetz
authors.initials: G
authors.lastname: Parsiegla
authors.affiliation: CNRS, Aix-Marseille Université, Enzymologie Interfaciale et Physiologie de la Lipolyse, UMR 7282, 31 chemin Joseph Aiguier, 13402 Marseille cedex 20, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Carrière
authors.affiliation: CNRS, Aix-Marseille Université, Enzymologie Interfaciale et Physiologie de la Lipolyse, UMR 7282, 31 chemin Joseph Aiguier, 13402 Marseille cedex 20, France. Electronic address: jfcavalier@imm.cnrs.fr.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Cavalier
mesh_terms: D000327:Adsorption; D000388:Air; D000818:Animals; D004285:Dogs; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008049:Lipase / Q000378:metabolism*; D008958:Models, Molecular; D010713:Phosphatidylcholines / Q000737:chemistry*; D011312:Pressure; D011485:Protein Binding; D013270:Stomach / Q000201:enzymology*; D013696:Temperature; D014867:Water
chemical_list: D010713:Phosphatidylcholines; D014867:Water; C015153:1,2-dilauroylphosphatidylcholine; D008049:Lipase
keywords: Enzyme adsorption; Interfacial enzymology; Kinetic parameters; Monomolecular film