Photoactive spatial proximity probes for binding pairs with epigenetic marks

•Photoassisted binding assay differentiates peptides with epigenetic marks.•The library-encoding strategy is compatible with automated peptide synthesis.•Methodology could be adapted for assaying solution phase libraries.

A new strategy for encoding polypeptide libraries with photolabile tags is developed. The photoassisted assay, based on conditional release of encoding tags only from bound pairs, can differentiate between peptides which have minor differences in a form of post-translational modifications with epigenetic marks. The encoding strategy is fully compatible with automated peptide synthesis. The encoding pendants are compact and do not perturb potential binding interactions.