title: Membranolytic activity of bile salts: influence of biological membrane properties and composition.
abstract: The two main steps of the membranolytic activity of detergents: 1) the partitioning of detergent molecules in the membrane and 2) the solubilisation of the membrane are systematically investigated. The interactions of two bile salt molecules, sodium cholate (NaC) and sodium deoxycholate (NaDC) with biological phospholipid model membranes are considered. The membranolytic activity is analysed as a function of the hydrophobicity of the bile salt, ionic strength, temperature, membrane phase properties, membrane surface charge and composition of the acyl chains of the lipids. The results are derived from calorimetric measurements (ITC, isothermal titration calorimetry). A thermodynamic model is described, taking into consideration electrostatic interactions, which is used for the calculation of the partition coefficient as well as to derive the complete thermodynamic parameters describing the interaction of detergents with biological membranes (change in enthalpy, change in free energy, change in entropy etc). The solubilisation properties are described in a so-called vesicle-to-micelle phase transition diagram. The obtained results are supplemented and confirmed by data obtained from other biophysical techniques (DSC differential scanning calorimetry, DLS dynamic light scattering, SANS small angle neutron scattering).
authors.affiliation: Martin-Luther-University Halle-Wittenberg, Institute of Chemistry, Physical Chemistry, Muehlpforte 1, D-06108 Halle/Saale, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Garidel
authors.forename: Annegret
authors.initials: A
authors.lastname: Hildebrand
authors.forename: Katja
authors.initials: K
authors.lastname: Knauf
authors.forename: Alfred
authors.initials: A
authors.lastname: Blume
mesh_terms: D001647:Bile Acids and Salts / Q000737:chemistry*; D002151:Calorimetry; D002152:Calorimetry, Differential Scanning; D002462:Cell Membrane / Q000737:chemistry; D003840:Deoxycholic Acid / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D008563:Membrane Lipids / Q000737:chemistry*; D044367:Phase Transition; D010743:Phospholipids / Q000737:chemistry; D053838:Scattering, Small Angle; D020358:Sodium Cholate / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics
chemical_list: D001647:Bile Acids and Salts; D008081:Liposomes; D008563:Membrane Lipids; D010743:Phospholipids; D003840:Deoxycholic Acid; D020358:Sodium Cholate