SPR measures changes in the “resonance” of light reflected from a gold film that has a “receptor” of interest attached to the gold. The resonance of the reflected light is proportional to the mass of whatever is attached to the gold film. Therefore, binding events are detected as changes in the resonance.

Binding of anything that can be placed in solution to anything that can be covalently attached to a chip.

This is still a debated question. The system is designed to have a "ligand" (which is often the larger species) in solution flowing past a bound "receptor" (which is often the smaller species) on the chip. Because flow characteristics and an "unstirred layer" phenomena exist for any liquid which is flowing in a tube, the accuracy of the binding constants which are determined has been questioned and in some instances been shown to be different by about an order of magnitude from constants determined in equilibrium experiments. To address this problem the SPR experiment is designed to measure binding at multiple different "ligand" concentrations and with a minimum "receptor" concentration on the chip. This results in a very low signal and necessitates a high degree of skill in the design and operation of the system.

There are essentially no limits on the size of the "ligand" or "receptor". SPR can detect binding of drugs with mol wt under 300 and of peptides, proteins of any size, protein complexes, organelles or whole cells. The affinity of the binding species for each other can be very low so interactions with high µM affinities can be characterized. Kinetics of binding and dissociation are measured as part of every experiment. The molecules from the flow channel that bind can be collected and analyzed after being released from the chip.

The Biacore 3000: This instrument is typically not available for "walk up" use and a PIP Core technician will perform all procedures. Those with appropriate training can discuss access to the instrument with Dr. Terlecky.

Consultation on experimental design Preparation of chips for experiments Running of experiments Use of Biacore analysis software and training in use of the software