An Unexpected Example of Protein‐Templated Click Chemistry

It all happened with a click: In a search for histone deacetylase (HDAC) inhibitors using in situ click chemistry, the first example of protein–Cu acceleration of the azide–alkyne cycloaddition reaction was uncovered. The copper center in the protein target HDAC8 catalyzed triazole formation between one azide–alkyne pair among 30 possibilities. These results provide a new route to HDAC inhibitors and a precedent for new types of protein-based catalysts for click chemistry.