Multivalent photoaffinity probe for labeling small molecule binding proteins.

Characterization of small molecule (SM)-protein interaction is of high importance in biomedical research such as target identification and proteomic profiling. Photo-cross-linking is a powerful and straightforward strategy to covalently capture SM's binding proteins. The DNA-based photoaffinity labeling method is able to capture SM's protein targets with high specificity but suffers low cross-linking efficiency, which limits its utility for low abundance and low affinity proteins. After screening a variety of cross-linkers, by utilizing the multivalency effect, the cross-linking efficiency was improved by nearly 7-fold without compromising probe specificity. The generality and performance of multivalent photoaffinity probes have been validated with a variety of SM-protein pairs in the complexity of cell lysates.