Biotin-free proximity labeling

Abstract
Compounds useful for biotin-free proximity labeling are provided. Also provided are methods for biotin-free labeling of biomolecules in proximity to a target in a cell, which involve attaching an engineered labeling enzyme to the target, and contacting the cell to a compound as disclosed, which is a substrate of the engineered labeling enzyme and which includes a label moiety, wherein the biomolecules in proximity to the target are labeled.