Patent ID: 8217145

Claim:
A method for producing in a translation system a protein comprising an unnatural amino acid at a selected position, the method comprising: (a) providing a translation system comprising: (i) a first unnatural amino acid that is phenylselenocysteine; (ii) a first orthogonal aminoacyl-tRNA synthetase (O-RS), wherein the O-RS is at least 90% identical to SEQ ID NO: 6 and comprises: a Trp at a position corresponding to position 32 of SEQ ID NO: 6 and a Gly at a position corresponding to position 70 of SEQ ID NO: 6; (iii) a first orthogonal tRNA (O-tRNA) comprising a polynucleotide sequence set forth in SEQ ID NO: 1, wherein said first O-RS preferentially aminoacylates said first O-tRNA with said phenylselenocysteine; and, (iv) a nucleic acid encoding said protein, wherein said nucleic acid comprises at least one selector codon that is recognized by said first O-tRNA; and, (b) incorporating said unnatural amino acid at said selected position in said protein during translation of said protein in response to said selector codon, thereby producing said protein comprising said unnatural amino acid at the selected position.