Enrichment of Specifically Labeled Proteins by an Immobilized Host Molecule

Chemical proteomics relies primarily on click-chemistry-based protein labeling and biotin-streptavidin enrichment, but these techniques have inherent limitations. Enrichment of intracellular proteins using a totally synthetic host–guest complex is described, overcoming the problem associated with the classical approach. We achieve this by affinity-based protein labeling with a target-specific probe molecule conjugated to a high-affinity guest (suberanilohydroxamic acid–ammonium-adamantane; SAHA-Ad) and then enriching the labeled species using a cucurbit[7]uril bead. This method shows high specificity for labeled molecules in a MDA-MB-231 breast cancer cell lysate. Moreover, this method shows promise for labeling proteins in live cells.