Surface Plasmon Resonance (SPR) is a biosensor technology enabling label-free and real- time measurement of protein-protein interactions. In the capture assay, the ligand of interest binds to the specific antibody that is immobilized on a chip. The kinetics of binding can then be measured. The principle uses of SPR analysis are to identify complimentary binding pairs of antibodies with recombinant antigen or to determine binding kinetics and affinity of antibodies with the parent antigen.
Ligand: The ligand should be homogeneous and more than 90% pure when used for covalent binding to the sensor chip. For one immobilization of a molecule using amine coupling, 1-10 µg is normally sufficient.
The properties of the ligand, which when known are helpful in experiments, are the molecular mass, iso-electric point and the number of lysine's.
Analyte: The analyte concentration of stock solutions should be between 0.1 - 1 mg/ml and free of particles and compounds with large refractive index (e.g. glycerol). The amount needed is about 10 - 100 mg depending on the KD.
The properties of the analyte that are helpful in experiments are the molecular mass (should be > 5 kDa for kinetic studies) and pI. The pI should be below nine; otherwise, a lot of non-specific binding is to be expected.
- The current turn-around for SPR projects is 4-8 weeks.
Some projects may take longer if there is a problem with the proteins or antibodies that requires extra sample manipulation before the analysis can be run.