A single type of chemical structure that shows up again and again in modern medicine is the amide bond that links a carbonyl group (C=O) to a nitrogen atom. They’re so ubiquitous that 117 of the top 200 small-molecule drugs by retail sales in 2023 feature at least one amide bond. And now, researchers have discovered a clever new way to reengineer natural enzymes to build amides from simple chemicals like aldehydes and amines.