Patent ID: 7524647

Claim:
A method of producing a protein in a cell with a keto amino acid at a specified position, the method comprising: growing, in an appropriate medium, the cell, where the cell comprises a nucleic acid that comprises at least one selector codon and encodes a protein; and, providing the keto amino acid, wherein the keto amino acid is a derivative of a tyrosine or a phenylalanine amino acid; wherein the cell further comprises: an orthogonal tRNA (O-tRNA) that functions in the cell and recognizes the selector codon; and, an orthogonal aminoacyl-tRNA synthetase (O-RS) comprising an amino acid sequence selected from SEQ ID NO: 18 or a conservative variation thereof comprising at least 90% identity with SEQ ID NO: 18; wherein the ORS further comprises as Ala or Leu at a position corresponding to position 32 and comprises Gly at a position corresponding to position 158 compared to wild type tyrosy 1 tRNA synthetase from Methanococcus jannaschii ; and incorporating the keto amino acid into the specified position in the protein during translation of the nucleic acid with the at least one selector codon, thereby producing the protein.