Therese W. Herling, David J. O’Connell, Mikael C. Bauer, Jonas Persson, Ulrich Weininger, Tuomas P.J. Knowles, and Sara Linse
Biophys J. 2016, 110(9), 1957–1966
In this paper, Herling et al demonstrate a microfluidic platform for the detection of protein-ligand interactions with an assay time on the second timescale and without the requirement for immobilization or the presence of a highly viscous matrix. They do this using a microfluidic free-flow electrophoresis platform. In this manner, they are able to determine the dissociation constant of calmodulin with a novel binding protein—creatine kinase, and look at how calcium concentration alters this.
The authors compare protein binding affinity measurements in free solution (obtained using free flow electrophoresis and thermophoresis), and on a surface (obtained using SPR), noting that SPR measurements report a considerably lower KD relative to the in solution methods, which correlate well.