Therese W. Herling, David J. O’Connell, Mikael C. Bauer, Jonas Persson, Ulrich Weininger, Tuomas P.J. Knowles, and Sara Linse
Biophys J. 2016 May 10; 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.