α-Ketoester-based photobiological switches: synthesis, peptide chain extension and assay against α-chymotrypsin

The design, synthesis, photoisomerism and biological testing of two peptide-based photoswitchable inhibitors of α-chymotrypsin are presented. The use of a dipeptide recognition sequence gave a ‘slow-tight binding’ inhibitor, while the introduction of a carbamate linker to the azobenzene gave a modest enhancement in photoswitching of enzyme activity for the photostationary state enriched in the (Z)-isomer over the (E)-isomer.