Chemists have coaxed a common enzyme into catalyzing the formation of an enantioselective carbon-nitrogen bond. The approach can generate the preferred enantiomer of amines and anilines within molecules of interest ( Nat. Chem. 2021, DOI: 10.1038/s41557-021-00794-z ). Such chiral C–N bonds are practically ubiquitous in pharmaceuticals, from antibiotics to anticancer compounds. Frances Arnold and other scientists from the California Institute of Technology and the University of Girona used directed evolution to engineer a dual-function enzyme that performs a two-step, asymmetric N–H insertion into a carbene intermediate. The enzyme can produce over 90% of the preferred enantiomer. Such selectivity is difficult using traditional organic synthesis methods. Zhen Liu , a postdoctoral researcher in Arnold’s lab and the paper’s first author, says nonenzymatic carbene N–H insertion requires two different catalysts: one to form the carbene intermediate and a second to donate a proton and produce the final aniline product. The team’s enzyme