New enzymes for green chemistry

Not satisfied with nature's vast catalytic repertoire, we want to create new enzymes and expand the space of genetically encoded chem. reactions. I will describe how we can use the most powerful biol. design process, evolution, to optimize existing enzymes and invent new ones. Mimicking nature's evolutionary tricks and using a little chem. intuition, we can generate whole new enzyme families that catalyze important reactions not (yet) known in nature, thereby adding new capabilities to the chem. of the biol. world and increasing the scope of mols. and materials we can build. I will show that heme proteins can catalyze an array of increasingly challenging carbene- and nitrene-transfer reactions and that these new activities can be enhanced by directed evolution. Unlike small-mol. catalysts described for some of these reactions, the new heme enzymes are made microbially from renewable resources, use earth-abundant iron, function in aq. media under ambient conditions, and are highly selective.