Patent ID: 8183012

Claim:
A composition comprising an aminoacyl-tRNA synthetase (RS), wherein the RS preferentially aminoacylates a tRNA with an unnatural amino acid; wherein the RS displays a lower K m for the unnatural amino acid than for any of the 20 common naturally occurring amino acids; wherein the RS also displays a higher K cat for the unnatural amino acid than for any of the 20 common naturally occurring amino acids; wherein the unnatural amino acid comprises a tyrosine analogue or derivative, a phenylalanine analogue or derivative, or a leucine analogue or derivative; wherein the RS is derived from a TyrRS or a LeuRS; wherein the RS comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 35-64 and conservative variants thereof; and wherein the tRNA is derived from a tRNATyr or a tRNALeu.