Characterisation of lipid-protein interactions using a surface plasmon resonance biosensor

The binding of proteins to lipid surfaces is of fundamental importance when considering the mechanisms of lipases and lipid transfer proteins. Current procedures for determining the binding constants suffer from problems related to poor sensitivity, poor reproducibility and to the use of restrictive assumptions in the analysis. We demonstrate here the use of the surface plasmon resonance biosensor to determine the association and dissociation kinetics of binding of cholesteryl ester transfer protein to the surface of emulsion particles of defined size and composition. Uncertainty about the emulsion valency, that is, the number of sites on the lipid particle occupied by the immobilised transfer protein on the biosensor surface, means that the association kinetics can only be characterised in terms of the product of the association rate constant and the concentration of sites, whereas the dissociation rate constant can be obtained unambiguously. The technique will prove useful in characterising the binding of proteins to lipid surfaces.