Equilibrium analysis of high affinity interactions using BIACORE
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Updated: Oct 11, 2026

The Importance of Correct Protein Concentration for Kinetics and Affinity Determination in Structure-function Analysis
Published on: March 17, 2010
D G Myszka1, M D Jonsen, B J Graves
1Huntsman Cancer Institute, University of Utah, 15 N. 2030 E., Room 2100, Salt Lake City, Utah, 84112-5330, USA. dmyszka@hci.utah.edu
Abstract:
BIACORE biosensors are useful for measuring reaction kinetics and calculating affinity constants for macromolecular interactions. However, one drawback with the flow system used in these instruments is that the standard injection procedures limit the amount of time available to collect association-phase data. This is especially problematic during equilibrium analysis of high affinity interactions. Using protein-DNA interactions as a model system, we demonstrate a simple method for overcoming this limitation. By placing the analyte directly into the running buffer we were able to deliver a continuous supply of protein to the sensor surfaces for greater than 12 h at a time. Complete equilibrium binding profiles were generated by changing the concentration of analyte and allowing the surface reactions to reequilibrate. Analyte concentrations were also decreased to demonstrate that the binding reactions were fully reversible. This method of analysis is a simple and convenient way of directly measuring equilibrium dissociation constants for very high affinity interactions.
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