Facile synthesis of peptide–porphyrin conjugates: Towards artificial catalase

A facile synthetic method for peptide-porphyrin conjugates containing four peptide units on one porphyrin was developed using chemoselective reactions. The key building blocks, 5,10,15,20-tetrakis(3-azidophenyl)porphyrin 1 and 5,10,15,20-tetrakis(5-azido-3-pyridyl)porphyrin 2, were efficiently synthesized and used as substrates for two well-known chemoselective reactions, traceless Staudinger ligation and copper-catalyzed azide alkyne cycloaddition (so-called click chemistry). Both reactions gave the desired compounds, and click chemistry was superior for our purpose. To confirm the value of the established methodology, nine peptide-porphyrin conjugates were synthesized, and their catalase- and peroxidase-like activity in water was evaluated. Our synthetic strategy is expected to be valuable for the preparation of artificial heme protein models.