Fig. 2
From: Rebooting life: engineering non-natural nucleic acids, proteins and metabolites in microorganisms
Expanding the genetic code via incorporation of nonstandard amino acids (nsAAs) into proteins. For successful site-specific insertion of ncAAs in proteins, an orthogonal tRNA/aminoacyl-tRNA synthetase (aaRS) pair is required that aminoacylate and incorporate nsAA or chemically close standard amino acid (sAA); without being recognized by the native tRNA and aaRS. The figure is adopted from Arranz-Gibert et al. [78] ©MDPI