Surface plasmon resonance in protein–membrane interactions

Surface plasmon resonance (SPR) has become one of the most important techniques for studying macromolecular interactions. The most obvious advantages of SPR over other techniques are: direct and rapid determination of association and dissociation rates of binding process, no need for labelling of protein or lipids, and small amounts of sample used in the assay (often nM concentrations of proteins). In biochemistry, SPR is used mainly to study protein–protein interactions. On the other hand, protein–membrane interactions, although crucial for many cell processes, are less well studied. Recent advances in the preparation of stable membrane-like surfaces and the commercialisation of sensor chips has enabled widespread use of SPR in protein–membrane interactions. One of the most popular is Biacore's L1 sensor chip that allows capture of intact liposomes or even subcellular preparations. Lipid specificity of protein–membrane interactions can, therefore, be easily studied by manipulating the lipid composition of the immobilised membrane. The number of published papers has increased steadily in the last few years and the examples include domains or proteins that participate in cell signalling, pore-forming proteins, membrane-interacting peptides, coagulation factors, enzymes, amyloidogenic proteins, prions, etc. This paper gives a brief overview of different membrane-mimetic surfaces that can be prepared on the surface of SPR chips, properties of liposomes on the surface of L1 chips and some selected examples of protein–membrane interactions studied with such system.