SIRT1 is an NAD+-dependent deacetylase, whose activators have potential therapeutic applications in age-related diseases. Here we report a new class of SIRT1 activators. The activation is dependent on the fluorophore labeled to the substrate. To elucidate the activation mechanism, we solved the crystal structure of SIRT3/ac-RHKKac-AMC complex. The structure revealed that the fluorophore blocked the H-bond formation and created a ...