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Seta-633 - A NIR Fluorescence Lifetime Label for Low-Molecular-Weight Analytes

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journal contribution
posted on 16.09.2009 by Yevgen A. Povrozin, Olga S. Kolosova, Olena M. Obukhova, Anatoliy L. Tatarets, Vadim I. Sidorov, Ewald A. Terpetschnig, Leonid D. Patsenker
We describe the photophysical properties of Seta-633, a commercially available near-infrared (NIR) dye, and its use as a fluorescent label to study the interaction between low-molecular-weight analytes and proteins using fluorescence lifetime as the readout parameter. In a model assay, we demonstrate that a biotinylated Seta-633 tracer binds to antibiotin with high specificity. Importantly, the lifetime of Seta-633−biotin increases about 1.8-fold upon binding to a specific antibody (antibiotin, MW = 160 kDa), while the titration with bovine serum albumin (BSA) or nonspecific antibody does not result in a noticeable change in lifetime. This behavior is contrary to that of fluorescent tracers like Cy5 or Alexa 647, which typically exhibit much smaller lifetime changes upon binding to antibodies.