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

Nat Biotechnol. 2011 Apr;29(4):357-60. doi: 10.1038/nbt.1790. Epub 2011 Mar 13.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amidohydrolases / metabolism
  • Cholera Toxin / metabolism
  • G(M1) Ganglioside / metabolism
  • Humans
  • Interferometry / methods*
  • Kinetics
  • Ligands
  • Membrane Proteins / metabolism*
  • Microscopy, Fluorescence
  • Protein Binding
  • Receptors, CXCR4 / metabolism
  • Receptors, GABA-B / metabolism
  • Refractometry / methods


  • Ligands
  • Membrane Proteins
  • Receptors, CXCR4
  • Receptors, GABA-B
  • G(M1) Ganglioside
  • Cholera Toxin
  • Amidohydrolases
  • fatty-acid amide hydrolase