CHEMISTRY DEPARTMENT SEMINAR
“Elucidating Interfacial Chemical Processes with Surface-Selective Spectroscopy Techniques”
Dr. Halil İ. Okur
Swiss Federal Institute of Technology at Lausanne (EPFL)
Ions differ in their ability to salt-out proteins from solutions as expressed in the lyotropic or Hofmeister series of cations and anions. Although it has been clear that the Hofmeister series is intimately connected to ion hydration and ion pairing, a molecular level detailed picture of the interactions between ions and biomacromolecules are elusive. In this talk, I will show molecular machinery of ion-specific interactions on biomacromolecules, namely, the cations only weakly binding to protein backbones, and guanidinium salts causing and preventing the hydrophobic collapse of biomacromolecules.
Besides the biomacromolecular surfaces, phospholipid assemblies such as lipid bilayers, and monolayers are the other abundant physiological interfaces of interest. For instance, three-dimensional phospholipid monolayers at hydrophobic/water interfaces can be found at the surface of adiposome organelles. Due to lack of surface selective diagnostics that are capable of investigating buried interfaces, the properties of such monolayers are not known. In order to study such systems in the laboratory, we first designed a well-controlled hydrophobic phase/phospholipid/water model system as a suspension in aqueous solution. Then, the effects of phospholipid acyl chain length, acyl chain saturation and the number of acyl tails per lipid on the hydration and structure of the monolayer properties are elucidated. Remarkably, the lyso-PC (single-tailed) lipids uniquely form more diluted and “patchy” 3D monolayers.
Date: September 21 (Friday)
Place: Faculty of Science Building, B Block, Seminar Room #Z-14
All interested are cordially invited.