By Peter J. Brescia, Applications Scientist, BioTek Instruments, Inc.
A variety of methods and reagents have been developed to efficiently label biomolecules. These labels greatly improve assay sensitivity in conjunction with modern analytical techniques and instrumentation. Many of these labeling methods involve covalent modifications of proteins or nucleic acids resulting in the addition of a fluorophore or a functional moiety via a flexible linker. The use of labeled reagents in a variety of experimental methods such as immunofluorescence, TR-FRET, and ELISA has been shown to provide substantial improvements in assay sensitivity while allowing sample and reagent conservation in a high-throughput context. Here we describe the analysis of protein-antibody conjugates labeled with biotin or digoxigenin using micro-volume spectral-scanning analysis in a microplate reader.