One of life’s many mysteries is how it ended up choosing only a set of 20 amino acids to build proteins for its wide catalog of organisms, from single-celled bacteria to behemoth whales. From a chemical standpoint, many of the canonical amino acids share similar chemical structures and properties, which might make them expendable. This raises an intriguing question: could life manage with one less amino acid?
Life with one less: Engineered bacteria break the 20-amino-acid rule
