Behaviour of the bovine brain phosphatidylethanolamine binding protein at the air/water interface

The cytosolic bovine brain PEBP is a basic protein of 21 kDa devoid of disulfide bridges. It has been shown to form stable monomolecular protein films at the air/water interface. In the course of time, the PEBP films expanded nearly three times probably as the result of protein unfolding at the interface. The PEBP diffusion from a protein solution towards the interface is very low in account of its high content in polar residues and of its widely β-sheet structure. The adsorption rate of PEBP at the air/water interface is dependent on the bulk concentration of the protein and the saturation of the surface occurs as early as the bulk concentration reaches 2.5×10−6 M in amino acid. The surface concentration of PEBP at saturation is less than 2×1018 amino acid/m2, a value in a 10 lower range than observed for other proteins of the same size and devoid of disulfide bridges.