Thesis presented December 19, 2002

Abstract:
The immobilization of proteins anchored to lipids at the air-water or solidwater interface let the proteins interact with other molecules in solution. In the case of the cell adhesion proteins named cadherins, this system mimics the surface of a cell. The interactions between the extracellular domains of cadherins require the presence of calcium ions. Monolayers of C-cadherin and VE-cadherin formed at the surface of water were studied by varying the calcium concentration. The apparent surface mass density of proteins was evaluated by ellipsometry. The electronic density profile of monolayers was determined by grazing incidence x-ray reflectivity. The results obtained suggest that the cadherins form anti-parallel complexes which can be partly dissociated by reducing the calcium concentration. Surface plasmons resonance was also used to evaluate the surface density of molecules deposited on a solid substrate.

Keywords:
Ellipsometry, X-ray Reflectivity, Cadherin, Surface Plasmon Resonance, Monolayers, Phospholipids, Cell adhesion

On-line thesis.