Label-free quantification of membrane-ligand interactions using backscattering interferometry

Department of Chemistry, The Scripps Research Institute, La Jolla, California, USA.
Nature Biotechnology (Impact Factor: 39.08). 03/2011; 29(4):357-60. DOI: 10.1038/nbt.1790
Source: PubMed

ABSTRACT Although membrane proteins are ubiquitous within all living organisms and represent the majority of drug targets, a general method for direct, label-free measurement of ligand binding to native membranes has not been reported. Here we show that backscattering interferometry (BSI) can accurately quantify ligand-receptor binding affinities in a variety of membrane environments. By detecting minute changes in the refractive index of a solution, BSI allows binding interactions of proteins with their ligands to be measured at picomolar concentrations. Equilibrium binding constants in the micromolar to picomolar range were obtained for small- and large-molecule interactions in both synthetic and cell-derived membranes without the use of labels or supporting substrates. The simple and low-cost hardware, high sensitivity and label-free nature of BSI should make it readily applicable to the study of many membrane-associated proteins of biochemical and pharmacological interest.

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