(S)-2-amino-6-((2-azidoethoxy)carbonylamino)hexanoic acid hydrochloride

H-L-Lys(EO-N3)-OH or H-L-Lys(Pryoc)-OH (HAA2090) are non-canonical amino acids suitable for click chemistry. They can be introduced site-specifically into recombinant proteins by the Pyrrolysyl-tRNA Synthetase/tRNA(CUA) Pair. Pyrrolysine (Pyl; HAA2830) is considered the 22nd proteinogenic amino acid. It is a naturally occurring, genetically coded amino acid used by some methanogenic archaea and one known bacterium in enzymes that are part of their methane-producing metabolism. It is similar to lysine, but with an added pyrroline ring linked to the end of the lysine side chain. It forms part of an unusual genetic code in these organisms. References: Genetic Encoding and Labeling of Aliphatic Azides and Alkynes in Recombinant Proteins via a Pyrrolysyl-tRNA Synthetase/tRNACUA Pair and Click Chemistry; D. P. Nguyen, H. Lusic, H. Neumann, P. B. Kapadnis, A. Deiters and J. W. Chin; J Am Chem Soc 2009; 131: 8720-8721. doi:10.1021/ja900553w. Expanding the Genetic Code of Yeast for Incorporation of Diverse Unnatural Amino Acids via a Pyrrolysyl-tRNA Synthetase/tRNA Pair; S. M. Hancock, R. Uprety, A. Deiters and J. W. Chin; J Am Chem Soc 2010; 132: 14819-14824. doi:10.1021/ja104609m. Expanding the Genetic Code of an Animal; S. Greiss and J. W. Chin; J Am Chem Soc 2011; 133: 14196-14199. doi:10.1021/ja2054034 Click Strategies for Single-Molecule Protein Fluorescence; S. Milles, S. Tyagi, N. Banterle, C. Koehler, V. VanDelinder, T. Plass, A. P. Neal and E. A. Lemke; J Am Chem Soc 2012; 134: 5187-5195. doi:10.1021/ja210587q. Genetic Encoding of a Bicyclo[6.1.0]nonyne-Charged Amino Acid Enables Fast Cellular Protein Imaging by Metal-Free Ligation; A. Borrmann, S. Milles, T. Plass, J. Dommerholt, J. M. M. Verkade, M. Wießler, C. Schultz, J. C. M. van Hest, F. L. van Delft and E. A. Lemke; ChemBioChem 2012; 13: 2094-2099. doi:10.1002/cbic.201200407. Expanding the genetic code of Drosophila melanogaster; A. Bianco, F. M. Townsley, S. Greiss, K. Lang and J. W. Chin; Nat Chem Biol 2012; 8: 748-750. doi:10.1038/nchembio.1043. Pyrrolysine Encoded by UAG in Archaea: Charging of a UAG-Decoding Specialized tRNA; G. Srinivasan, C. M. James and J. A. Krzycki; Science 2002; 296: 1459-1462. doi:10.1126/science.1069588. A New UAG-Encoded Residue in the Structure of a Methanogen Methyltransferase; B. Hao, W. Gong, T. K. Ferguson, C. M. James, J. A. Krzycki and M. K. Chan; Science 2002; 296: 1462-1466. doi:10.1126/science.1069556. Direct charging of tRNACUA with pyrrolysine in vitro and in vivo; S. K. Blight, R. C. Larue, A. Mahapatra, D. G. Longstaff, E. Chang, G. Zhao, P. T. Kang, K. B. Green-Church, M. K. Chan and J. A. Krzycki; Nature 2004; 431: 333-335. doi:10.1038/nature02895