title: Structure and dynamics of lipid monolayers: implications for enzyme catalysed lipolysis.
abstract: We have investigated the role of the substrate on the interfacial activation of lipases by an interdisciplinary study of the structure and dynamics of 1,2-sn dipalmitoylglycerol monolayers at distinct surface pressures. The diglyceride Langmuir film undergoes two phase transitions occurring at 38.3 and 39.8 A2 per molecule. The first transition is unique for diglyceride molecules and is driven by a reorganization of the headgroups causing a change in the hydrophobicity of the oil-water interface. X-ray diffraction studies of different mesophases shows that in the two highest pressure phases, the alkyl chains pack in an hexagonal structure relaxing to a distorted-hexagonal lattice in the lowest pressure phase with the alkyl chains tilted by approximately 14 degrees in a direction close to a nearest neighbour direction.
authors.affiliation: Chemistry Department III, H.C. Orsted Institutet, University of Copenhagen, Denmark.
authors.forename: G H
authors.initials: GH
authors.lastname: Peters
authors.forename: S
authors.initials: S
authors.lastname: Toxvaerd
authors.forename: N B
authors.initials: NB
authors.lastname: Larsen
authors.forename: T
authors.initials: T
authors.lastname: Bjørnholm
authors.forename: K
authors.initials: K
authors.lastname: Schaumburg
authors.forename: K
authors.initials: K
authors.lastname: Kjaer
mesh_terms: D003198:Computer Simulation; D004075:Diglycerides / Q000737:chemistry / Q000378:metabolism; D008049:Lipase / Q000378:metabolism*; D008066:Lipolysis; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D008956:Models, Chemical; D010169:Palmitic Acids / Q000737:chemistry; D011312:Pressure; D013379:Substrate Specificity; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D004075:Diglycerides; D008563:Membrane Lipids; D010169:Palmitic Acids; D008049:Lipase