Genetically Encoded Libraries of Nonstandard Peptides
Figure 5
Selection of nonstandard peptides from libraries generated by aaRS-based genetic code reprogramming. Nonproteinogenic amino acids were charged onto tRNA by aaRS misacylation. The non-standard peptide libraries were expressed in a reconstituted cell-free translation system in the mRNA display format. (a) Selection of non-standard peptides from libraries containing 12 different nonproteinogenic amino acids (12 proteinogenic amino acid analogs). The nonproteinogenic amino acids were reassigned to NNK codons. The peptides were cyclized by the addition of 1,3-di(bromomethyl)benzene to react with the sulfhydryl groups on the two cysteine residues of the peptides. The cyclic peptide library, containing 10 random residues, was used for the selection of thrombin inhibitors. (b) Selection of sortase A binding lantipeptides. L-4-selenalysine was reassigned to the AAA codon. The L-4-selenalysine residue was oxidized and converted to dehydroalanine, which was used for cyclization of the peptide. The cyclic peptide library, containing nine random residues, was used for selection.
