title: Accumulation of phosphatidylcholine on gut mucosal surface is not dominated by electrostatic interactions.
abstract: The accumulation of phosphatidylcholine (PC) in the intestinal mucus layer is crucial for the protection of colon epithelia from the bacterial attack. It has been reported that the depletion of PC is a distinct feature of ulcerative colitis. Here we addressed the question how PC interacts with its binding proteins, the mucins, which may establish the hydrophobic barrier against colonic microbiota. In the first step, the interactions of dioleoylphosphatidylcholine (DOPC) with two mucin preparations from porcine stomach, have been studied using dynamic light scattering, zeta potential measurement, and Langmuir isotherms, suggesting that mucin binds to the surface of DOPC vesicles. The enthalpy of mucin-PC interaction could be determined by isothermal titration calorimetry. The high affinity to PC found for both mucin types seems reasonable, as they mainly consist of mucin 2, a major constituent of the flowing mucus. Moreover, by the systematic variation of net charges, we concluded that the zwitterionic DOPC has the strongest binding affinity that cannot be explained within the electrostatic interactions between charged molecules.
authors.affiliation: Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg University, D69120 Heidelberg, Germany.
authors.forename: Agatha
authors.initials: A
authors.lastname: Korytowski
authors.affiliation: Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg University, D69120 Heidelberg, Germany.
authors.forename: Wasim
authors.initials: W
authors.lastname: Abuillan
authors.affiliation: Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg University, D69120 Heidelberg, Germany.
authors.forename: Federico
authors.initials: F
authors.lastname: Amadei
authors.affiliation: Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg University, D69120 Heidelberg, Germany.
authors.forename: Ali
authors.initials: A
authors.lastname: Makky
authors.affiliation: Heidelberg University Biochemistry Center (BZH), D69120 Heidelberg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gumiero
authors.affiliation: Heidelberg University Biochemistry Center (BZH), D69120 Heidelberg, Germany.
authors.forename: Irmgard
authors.initials: I
authors.lastname: Sinning
authors.affiliation: Department of Internal Medicine IV, University Clinics of Heidelberg, D69120 Heidelberg, Germany.
authors.forename: Annika
authors.initials: A
authors.lastname: Gauss
authors.affiliation: Department of Internal Medicine IV, University Clinics of Heidelberg, D69120 Heidelberg, Germany. Electronic address: Wolfgang.Stremmel@med.uni-heidelberg.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Stremmel
authors.affiliation: Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg University, D69120 Heidelberg, Germany; Institute for Integrated Cell-Material Science (WPI iCeMS), Kyoto University, 606-8501 Kyoto, Japan. Electronic address: tanaka@uni-heidelberg.de.
authors.forename: Motomu
authors.initials: M
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D007413:Intestinal Mucosa / Q000378:metabolism*; D008027:Light; D009077:Mucins / Q000378:metabolism; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism*; D012542:Scattering, Radiation; D055672:Static Electricity; D013552:Swine
chemical_list: D009077:Mucins; D010713:Phosphatidylcholines; C017251:1,2-oleoylphosphatidylcholine
keywords: Electrostatics; Isothermal titration calorimetry; Light scattering; Lipid-protein interaction; Mucin; Ulcerative colitis