Measuring complexation by single-molecule fluorescence anisotropy

The complexation of a fluorescent probe by a target protein was observed by single-molecule fluorescence anisotropy. Free and bound states, heterogeneities, and rare binding events can all be observed by this approach. Fluorophore-conjugated biotin was used to bind to NeutrAvidin as a proof-of-concept case. Molecular interactions were observed that could not be elucidated with conventional (ensemble) measurements.