title: A Langmuir monolayer study of the action of phospholipase A2 on model phospholipid and mixed phospholipid-GM1 ganglioside membranes.
abstract: Polarization-modulation infrared reflection-absorption spectroscopy, surface pressure measurements and thermodynamic analysis were used to study enzymatic hydrolysis of lipid monolayers at the air/water interface. The Ca(2+)-requiring pork pancreatic phospholipase A2 was used as a catalyst. The substrates were pure 1,2-dilauroyl-sn-glycero-3-phosphocholine or mixed 1,2-dilauroyl-sn-glycero-3-phosphocholine - monosialotetrahexosylganglioside Langmuir films. The physicochemical properties of the monolayers were established with the aim of a correlation with enzyme activity. The infrared spectra were acquired upon the advancement of the catalysis; the latter was studied at a controlled surface pressure and area of the film. Changes of the intensity and frequency of different infrared signals characteristic for the two lipids were correlated with modification of the properties of the monolayer due to hydrolysis. The amide I signal characteristic for peptides permitted detecting the enzyme adsorbed at the interface. The thermodynamic and infrared results indicate that monosialotetrahexosylganglioside increases H-bonding of the lipid polar heads in the films. This effect, which may be responsible for the low activity of phospholipase A2 in the mixed films, could be used for developing enzyme-resistant lipid systems.
authors: Carl von Ossietzky University of Oldenburg, Center of Interface Science (CIS), Department of Pure and Applied Chemistry, D-26111 Oldenburg, Germany.
authors: Wiebke
authors: W
authors: Schulte
authors: Department of Physical Chemistry and Electrochemistry, Faculty of Chemistry, Jagiellonian University, ul. R. Ingardena 3, 30-060 Krakow, Poland.
authors: Monika
authors: M
authors: Orlof
authors: Carl von Ossietzky University of Oldenburg, Center of Interface Science (CIS), Department of Pure and Applied Chemistry, D-26111 Oldenburg, Germany.
authors: Izabella
authors: I
authors: Brand
authors: Department of Physical Chemistry and Electrochemistry, Faculty of Chemistry, Jagiellonian University, ul. R. Ingardena 3, 30-060 Krakow, Poland. Electronic address: bkorch@chemia.uj.edu.pl.
authors: Beata
authors: B
authors: Korchowiec
authors: Structure et Réactivité des Systèmes Moléculaires Complexes, UMR CNRS 7565, Faculté des Sciences et Techniques, Université de Lorraine, 54506 Vandœuvre-lès-Nancy, France. Electronic address: ewa.rogalska@univ-lorraine.fr.
authors: Ewa
authors: E
authors: Rogalska
mesh_terms: D000818:Animals; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D004789:Enzyme Activation; D005677:G(M1) Ganglioside / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008968:Molecular Conformation; D010179:Pancreas / Q000201:enzymology; D054467:Phospholipases A2 / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D013499:Surface Properties; D013552:Swine
chemical_list: D010743:Phospholipids; D005677:G(M1) Ganglioside; D054467:Phospholipases A2; D002118:Calcium
keywords: Ganglioside; Langmuir isotherms; Lipid monolayer; Phospholipid; Polarization-modulation infrared reflection-absorption spectroscopy