The ascent of man(made oxidoreductases)

•Here we highlight our recent advances in de novo enzyme design.•Heme C-binding maquettes with minimal complexity serve as promiscuous and efficient enzymes.•Well-defined substrate binding sites are possibly not required for efficient oxidoreductase catalysis. Though established 40 years ago, the field of de novo protein design has recently come of age, with new designs exhibiting an unprecedented level of sophistication in structure and function. With respect to catalysis, de novo enzymes promise to revolutionise the industrial production of useful chemicals and materials, while providing new biomolecules as plug-and-play components in the metabolic pathways of living cells. To this end, there are now de novo metalloenzymes that are assembled in vivo, including the recently reported C45 maquette, which can catalyse a variety of substrate oxidations with efficiencies rivalling those of closely related natural enzymes. Here we explore the successful design of this de novo enzyme, which was designed to minimise the undesirable complexity of natural proteins using a minimalistic bottom-up approach.