A fluorescence correlation spectroscopy-based assay for fragment screening of slowly inhibiting protein-peptide interaction inhibitors.

A fluorescence correlation spectroscopy (FCS)-based competitive binding assay to screen fragment-size compounds that weakly and slowly inhibit protein-peptide interactions was established. The interactions were detected by the increased diffusion time of a fluorescently labeled peptide probe after binding to its interacting protein. We analyzed the interactions between the c-Cbl TKB ...
domain and phosphopeptides derived from ZAP-70, APS, and EGFR with the FCS assay and obtained 6 hit fragments that bound to the c-Cbl interaction sites. The binding amounts of the fragments were measured by direct binding measurements using surface plasmon resonance, and 5 fragments were found to bind selectively. The effect of 2 of the 5 fragments on the interaction with c-Cbl and the peptide exhibited strong time dependency. Furthermore, the inhibition by the selected 5 fragments on the protein-peptide interaction was confirmed by their effect on pull-down assays of c-Cbl with the biotin-conjugated interaction peptides. These results indicate the advantage of our FCS-based assay to study the time-dependent binding of compounds to their target protein.
Mesh Terms:
Animals, Binding, Competitive, Mice, Peptides, Phosphopeptides, Protein Binding, Protein Interaction Mapping, Proteins, Proto-Oncogene Proteins c-cbl, Spectrometry, Fluorescence
Anal. Biochem.
Date: Jul. 01, 2010
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