Immobilization through adsorption of luciferase on Langmuir-Blodgett films. Influence of the hydrophilicity or hydrophobicity of the surface on the enzyme kinetic behavior

Firefly luciferase aas immobilized through adsorption on lipidic Langmuir-Blodgett films whose surfaces were either hydrophilic or hydrophobic. Three different hydrophilic surfaces were constituted by the following polar head groups: carboxylic moieties of behenic acid, choline and phosphate of DPPC and DPPA, and N-acetylglucosamine of a particular glycolipid. The three different hydrophobic surfaces corresponding to the hydrocarbon tails of these molecules were also tested. The enzyme adsorption step studied through FTIR spectroscopy implied either electrostatic or hydrophobic interactions which led to different association strengths between the protein and the surface. These protein-surface interactions were modulated by the hydrophilic or hydrophobic character of the groups constituting the surfaces. The luciferase was active after adsorption, as revealed by bioluminescence detection, but the close contact between the protein and the film surface provoked a change in its kinetic behavior whatever the nature of tbe surface was.