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Non‐Canonical Amino Acids in Protein Polymer Design
Abstract
Protein polymers can be prepared with essentially absolute control of chain length, sequence, and stereochemistry through biological synthesis in microbial hosts. But for the polymer chemist, the twenty “canonical” amino acids provide an unacceptably small set of starting materials for macromolecular design. In the past several years, powerful techniques have been developed to introduce non‐natural (non‐canonical) amino acids containing a wide variety of functional groups into recombinant proteins. This review presents the methods currently available for the introduction of non‐natural amino acids into engineered proteins both in vitro and in vivo. Methods for multiple‐ and single‐site introduction are described. Recent applications of these methods are also addressed, particularly the development of biosensors, novel surfaces, and materials.
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“Protein-based hydrogels can be outfitted with a broad range of chemical functionalities by introducing noncanonical amino acids208,209; they can also be readily tailored to a wide variety of biomedical contexts210,211 and made thermally responsive212,213.”
From Towards organoid culture without Matrigel (2021) · cites this paper as [209]
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Cites
Agard, N. J., Prescher, J. A., & Bertozzi, C. R. (2004) · Journal of the American Chemical Society · doi:10.1021/ja044996f · Cited by 3,160
Cell Surface Engineering by a Modified Staudinger Reaction
Saxon, E., & Bertozzi, C. R. (2000) · Science · doi:10.1126/science.287.5460.2007 · Cited by 2,463
Expanding the Genetic Code of Escherichia coli
Wang, L., Brock, A., Herberich, B., & Schultz, P. G. (2001) · Science · doi:10.1126/science.1060077 · Cited by 1,504
A General Method for Site-specific Incorporation of Unnatural Amino Acids into Proteins
Noren, C. J., Anthony-Cahill, S. J., Griffith, M. C., & Schultz, P. G. (1989) · Science · doi:10.1126/science.2649980 · Cited by 1,019
Hendrickson, W. A., Horton, J. R., & LeMaster, D. M. (1990) · The EMBO Journal · doi:10.1002/j.1460-2075.1990.tb08287.x · Cited by 1,015
Kiick, K. L., Saxon, E., Tirrell, D. A., & Bertozzi, C. R. (2001) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.012583299 · Cited by 911
Self-citationWang, L., & Schultz, P. G. (2004) · Angewandte Chemie International Edition · doi:10.1002/anie.200460627 · Cited by 661
Cell Surface Labeling of Escherichia coli via Copper(I)-Catalyzed [3+2] Cycloaddition
Link, A. J., & Tirrell, D. A. (2003) · Journal of the American Chemical Society · doi:10.1021/ja036765z · Cited by 578
Self-citationCode for collagen's stability deciphered
Holmgren, S. K., Taylor, K. M., Bretscher, L. E., & Raines, R. T. (1998) · Nature · doi:10.1038/33573 · Cited by 499
Modern Separation Techniques for the Efficient Workup in Organic Synthesis
Tzschucke, C. C., Märkert, C., Bannwarth, W., Roller, S., Hebel, A., & Haag, R. (2002) · Angewandte Chemie International Edition · doi:10.1002/1521-3773(20021104)41:21 · Cited by 354
[28] Phase determination from multiwavelength anomalous diffraction measurements
Hendrickson, W. A., & Ogata, C. M. (1997) · Methods in enzymology on CD-ROM/Methods in enzymology · doi:10.1016/s0076-6879(97)76074-9 · Cited by 349
Budiša, N., Steipe, B., Demange, P., Eckerskorn, C., Kellermann, J., & Huber, R. (1995) · European Journal of Biochemistry · doi:10.1111/j.1432-1033.1995.0788h.x · Cited by 340
Beene, D. L., Brandt, G. S., Zhong, W., Zacharias, N. M., Lester, H. A., & Dougherty, D. A. (2002) · Biochemistry · doi:10.1021/bi020266d · Cited by 300
Presentation and Detection of Azide Functionality in Bacterial Cell Surface Proteins
Link, A. J., Vink, M. K. S., & Tirrell, D. A. (2004) · Journal of the American Chemical Society · doi:10.1021/ja047629c · Cited by 297
Self-citationBiosynthesis by Escherichia coli of active altered proteins containing selenium instead of sulfur
Cowie, D. B., & Cohen, G. N. (1957) · Biochimica et Biophysica Acta · doi:10.1016/0006-3002(57)90003-3 · Cited by 290
Efficient Incorporation of Unsaturated Methionine Analogues into Proteins in Vivo
van Hest, J. C. M., Kiick, K. L., & Tirrell, D. A. (2000) · Journal of the American Chemical Society · doi:10.1021/ja992749j · Cited by 268
Self-citationBudiša, N. (2004) · Angewandte Chemie International Edition · doi:10.1002/anie.200300646 · Cited by 263
Selective Dye-Labeling of Newly Synthesized Proteins in Bacterial Cells
Beatty, K. E., Xie, F., Wang, Q., & Tirrell, D. A. (2005) · Journal of the American Chemical Society · doi:10.1021/ja054643w · Cited by 252
Self-citationBiosynthetic site-specific incorporation of a non-natural amino acid into a polypeptide
Bain, J. D., Diala, E. S., Glabe, C. G., Dix, T. A., & Chamberlin, A. R. (1989) · Journal of the American Chemical Society · doi:10.1021/ja00202a052 · Cited by 250
Unnatural amino acids as probes of protein structure and function
Dougherty, D. D. (2000) · Current Opinion in Chemical Biology · doi:10.1016/s1367-5931(00)00148-4 · Cited by 243
Budiša, N., Steipe, B., Demange, P., et al. (1995) · European Journal of Biochemistry · doi:10.1111/j.1432-1033.1995.tb20622.x · Cited by 225
Furter, R. (1998) · Protein Science · doi:10.1002/pro.5560070223 · Cited by 216
THE EFFECT OF AMINO ACID ANALOGUES ON GROWTH AND PROTEIN SYNTHESIS IN MICROORGANISMS
Richmond, M. H. (1962) · Bacteriological Reviews · doi:10.1128/br.26.4.398-420.1962 · Cited by 206
Expansion of the Genetic Code Enables Design of a Novel “Gold” Class of Green Fluorescent Proteins
Bae, J. H., Rubini, M., Jung, G., Wiegand, G., Seifert, M. H. J., Azim, M. K., Kim, J.-S., Zumbusch, A., Holak, T. A., Moroder, L., et al. (2003) · Journal of Molecular Biology · doi:10.1016/s0022-2836(03)00364-4 · Cited by 204
“Chemical aminoacylation” of tRNA's
Hecht, S. M., Alford, B. L., KURODA, Y., & Kitano, S. (1978) · Journal of Biological Chemistry · doi:10.1016/s0021-9258(17)30417-9 · Cited by 194
Link, A. J., Vink, M. K. S., Agard, N. J., Prescher, J. A., Bertozzi, C. R., & Tirrell, D. A. (2006) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.0601167103 · Cited by 189
Self-citationMunier, R. L., & Cohen, G. N. (1959) · Biochimica et Biophysica Acta · doi:10.1016/0006-3002(59)90011-3 · Cited by 176
[15] Biosynthetic method for introducing unnatural amino acids site-specifically into proteins
Ellman, J. A., Mendel, D., Anthony‐Cahill, S. J., Noren, C. J., & Schultz, P. G. (1991) · Methods in enzymology on CD-ROM/Methods in enzymology · doi:10.1016/0076-6879(91)02017-4 · Cited by 174
Evolution of Nitrate Reductase: Molecular and Structural Variations on a Common Function
Stolz, J. F., & Basu, P. (2002) · ChemBioChem · doi:10.1002/1439-7633(20020301)3:2/3 · Cited by 171
Self-citationTang, Y., & Tirrell, D. A. (2001) · Journal of the American Chemical Society · doi:10.1021/ja016652k · Cited by 170
Self-citationProgrammed Self-Sorting of Coiled Coils with Leucine and Hexafluoroleucine Cores
Bilgiçer, B., Xing, X., & Kumar, K. (2001) · Journal of the American Chemical Society · doi:10.1021/ja016767o · Cited by 169
A Coiled Coil with a Fluorous Core
Bilgiçer, B., Fichera, A., & Kumar, K. (2001) · Journal of the American Chemical Society · doi:10.1021/ja002961j · Cited by 164
Stabilization of Coiled-Coil Peptide Domains by Introduction of Trifluoroleucine
Tang, Y., Ghirlanda, G., Vaidehi, N., Kua, J., Mainz, D. T., Goddard, W. A., DeGrado, W. F., & Tirrell, D. A. (2001) · Biochemistry · doi:10.1021/bi0022588 · Cited by 164
Self-citationArtificial Polypeptide Scaffold for Protein Immobilization
Zhang, K., Diehl, M. R., & Tirrell, D. A. (2005) · Journal of the American Chemical Society · doi:10.1021/ja051457h · Cited by 156
Self-citationHohsaka, T., Ashizuka, Y., Taira, H., Murakami, H., & Sisido, M. (2001) · Biochemistry · doi:10.1021/bi0108204 · Cited by 153
Datta, D., Wang, P., Carrico, I. S., Mayo, S. L., & Tirrell, D. A. (2002) · Journal of the American Chemical Society · doi:10.1021/ja0177096 · Cited by 139
Self-citationBreaking the Degeneracy of the Genetic Code
Kwon, I., Kirshenbaum, K., & Tirrell, D. A. (2003) · Journal of the American Chemical Society · doi:10.1021/ja0350076 · Cited by 131
Self-citationSykes, B. D., Weingarten, H. I., & Schlesinger, M. J. (1974) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.71.2.469 · Cited by 109
Mursinna, R. S., Lincecum, T. L., & Martinis, S. A. (2001) · Biochemistry · doi:10.1021/bi002915w · Cited by 108
Cohen, G. N., & Munier, R. L. (1959) · Biochimica et Biophysica Acta · doi:10.1016/0006-3002(59)90007-1 · Cited by 108
Identification of an expanded set of translationally active methionine analogues in Escherichia coli
Kiick, K. L., Weberskirch, R., & Tirrell, D. A. (2001) · FEBS Letters · doi:10.1016/s0014-5793(01)02657-6 · Cited by 105
Self-citationYoshikawa, E., Fournier, M. J., Mason, T. L., & Tirrell, D. A. (1994) · Macromolecules · doi:10.1021/ma00097a029 · Cited by 104
Self-citationKodama, K., Fukuzawa, S., Nakayama, H., Kigawa, T., Sakamoto, K., Yabuki, T., Matsuda, N., Shirouzu, M., Takio, K., Tachibana, K., et al. (2005) · ChemBioChem · doi:10.1002/cbic.200500290 · Cited by 102
On the Incorporation of 5',5',5'-Trifluoroleucine into Proteins of E. coli *
Rennert, O. M., & Anker, H. S. (1963) · Biochemistry · doi:10.1021/bi00903a013 · Cited by 100
Tang, Y., & Tirrell, D. A. (2002) · Biochemistry · doi:10.1021/bi026130x · Cited by 99
Self-citationEfficient introduction of aryl bromide functionality into proteins in vivo
Sharma, N., Furter, R., Kast, P., & Tirrell, D. A. (2000) · FEBS Letters · doi:10.1016/s0014-5793(00)01120-0 · Cited by 99
Self-citationCo-translational Incorporation ofTrans-4-Hydroxyproline into Recombinant Proteins in Bacteria
Buechter, D. D., Paolella, D. N., Leslie, B. S., Brown, M. S., Mehos, K. A., & Gruskin, E. A. (2002) · Journal of Biological Chemistry · doi:10.1074/jbc.m209364200 · Cited by 98
Baldini, G., Martoglio, B., Schachenmann, A., Zugliani, C., & Brunner, J. (1988) · Biochemistry · doi:10.1021/bi00420a054 · Cited by 97
Huang, W., Baker, G. L., & Bruening, M. L. (2001) · Angewandte Chemie International Edition · doi:10.1002/1521-3773(20010417)40:8 · Cited by 96
Self-citationSelf-Association and Membrane-Binding Behavior of Melittins Containing Trifluoroleucine
Niemz, A., & Tirrell, D. A. (2001) · Journal of the American Chemical Society · doi:10.1021/ja004351p · Cited by 95
Self-citationIn vivo incorporation of multiple unnatural amino acids through nonsense and frameshift suppression
Rodriguez, E. A., Lester, H. A., & Dougherty, D. A. (2006) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.0510817103 · Cited by 93
Kim, W., McMillan, R. A., Snyder, J. P., & Conticello, V. P. (2005) · Journal of the American Chemical Society · doi:10.1021/ja054105j · Cited by 89
Five-base codons for incorporation of nonnatural amino acids into proteins
Hohsaka, T. (2001) · Nucleic Acids Research · doi:10.1093/nar/29.17.3646 · Cited by 85
Kiick, K. L., & Tirrell, D. A. (2000) · Tetrahedron · doi:10.1016/s0040-4020(00)00833-4 · Cited by 83
Self-citationRoss, J. B. A., Senear, D. F., Waxman, E. L., Kombo, B. B., Rusinova, E. V., Huang, Y. T., Laws, W. R., & Hasselbacher, C. A. (1992) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.89.24.12023 · Cited by 80
Matsuda, S., Ishikubo, A., Kuzuya, A., Yashiro, M., & Komiyama, M. (1998) · Angewandte Chemie International Edition · doi:10.1002/(sici)1521-3773(19981217)37:23 · Cited by 78
Different Effects of 4-Hydroxyproline and 4-Fluoroproline on the Stability of Collagen Triple Helix
Nishi, Y., Uchiyama, S., Doi, M., Nishiuchi, Y., Nakazawa, T., Ohkubo, T., & Kobayashi, Y. (2005) · Biochemistry · doi:10.1021/bi047887m · Cited by 76
Evolving Proteins of Novel Composition
Montclare, J. K., & Tirrell, D. A. (2006) · Angewandte Chemie International Edition · doi:10.1002/anie.200600088 · Cited by 73
Self-citationNaasz, R., Arnold, L. A., Minnaard, A. J., & Feringa, B. L. (2001) · PubMed · doi:10.1002/1521-3773(20010302)40:5 · Cited by 72
Stabilization of bzip Peptides through Incorporation of Fluorinated Aliphatic Residues
Son, S.-H., Tanrikulu, I. C., & Tirrell, D. (2006) · ChemBioChem · doi:10.1002/cbic.200500420 · Cited by 70
Self-citationKim, W., George, A., Evans, M., & Conticello, V. P. (2004) · ChemBioChem · doi:10.1002/cbic.200400052 · Cited by 70
Kothakota, S., Mason, T. L., Tirrell, D. A., & Fournier, M. J. (1995) · Journal of the American Chemical Society · doi:10.1021/ja00106a064 · Cited by 68
Self-citationRational Design to Block Amino Acid Editing of a tRNA Synthetase
Mursinna, R. S., & Martinis, S. A. (2002) · Journal of the American Chemical Society · doi:10.1021/ja025879s · Cited by 65
Budiša, N. (2005) · Wiley eBooks · doi:10.1002/3527607188 · Cited by 63
Ohtsuki, T., Manabe, T., & Sisido, M. (2005) · FEBS Letters · doi:10.1016/j.febslet.2005.11.010 · Cited by 55
Köhrer, C. (2004) · Nucleic Acids Research · doi:10.1093/nar/gkh959 · Cited by 54
Wang, P., Fichera, A., Kumar, K., & Tirrell, D. A. (2004) · Angewandte Chemie International Edition · doi:10.1002/anie.200454036 · Cited by 54
Self-citationA carbene-yielding amino acid for incorporation into peptide photoaffinity reagents
Shih, L. B., & Bayley, H. (1985) · Analytical Biochemistry · doi:10.1016/0003-2697(85)90094-6 · Cited by 53
Hohsaka, T., Muranaka, N., Komiyama, C., Matsui, K., Takaura, S., Abe, R., Murakami, H., & Sisido, M. (2004) · FEBS Letters · doi:10.1016/s0014-5793(04)00099-7 · Cited by 51
Incorporation of monofluorotryptophans into protein during the growth of Escherichia coli
Browne, D. T., Kenyon, G. L., & Hegeman, G. D. (1970) · Biochemical and Biophysical Research Communications · doi:10.1016/0006-291x(70)90750-3 · Cited by 51
Incorporation of the amino acid analog tryptazan into the protein of Escherichia coli
Brawerman, G., & Yčas, M. (1957) · Archives of Biochemistry and Biophysics · doi:10.1016/0003-9861(57)90331-4 · Cited by 51
Dunn, B. M., DiBello, C., Kirk, K. L., Cohen, L. A., & CHAIKEN, I. M. (1974) · Journal of Biological Chemistry · doi:10.1016/s0021-9258(19)42252-7 · Cited by 50
Pal, P. P., Bae, J. H., Azim, M. K., Hess, P., Friedrich, R., Huber, R., Moroder, L., & Budiša, N. (2005) · Biochemistry · doi:10.1021/bi0484825 · Cited by 46
Bae, J. H., Alefelder, S., Kaiser, J. T., Friedrich, R., Moroder, L., Huber, R., & Budiša, N. (2001) · Journal of Molecular Biology · doi:10.1006/jmbi.2001.4699 · Cited by 46
Hamada, H., Kameshima, N., Szymańska, A., Wegner, K., Łankiewicz, L., Shinohara, H., Taki, M., & Sisido, M. (2005) · Bioorganic & Medicinal Chemistry · doi:10.1016/j.bmc.2005.03.014 · Cited by 42
Dougherty, M. J., Kothakota, S., Mason, T. L., Tirrell, D. A., & Fournier, M. J. (1993) · Macromolecules · doi:10.1021/ma00059a045 · Cited by 41
Self-citationEichler, J. F., Cramer, J. C., Kirk, K. L., & Bann, J. G. (2005) · ChemBioChem · doi:10.1002/cbic.200500249 · Cited by 39
Wong, C.-Y., & Eftink, M. R. (1998) · Biochemistry · doi:10.1021/bi971862o · Cited by 38
Influence of global fluorination on chloramphenicol acetyltransferase activity and stability
Panchenko, T., Zhu, W. W., & Montclare, J. K. (2006) · Biotechnology and Bioengineering · doi:10.1002/bit.20910 · Cited by 37
Broos, J., Gabellieri, E., Biemans‐Oldehinkel, E., & STRAMBINI, G. B. (2003) · Protein Science · doi:10.1110/ps.03142003 · Cited by 35
Brooks, B., Phillips, R. S., & Benisek, W. F. (1998) · Biochemistry · doi:10.1021/bi980454x · Cited by 33
Effect of photo-immobilization of epidermal growth factor on the cellular behaviors
Ogiwara, K., Nagaoka, M., Cho, C., & Akaike, T. (2006) · Biochemical and Biophysical Research Communications · doi:10.1016/j.bbrc.2006.04.001 · Cited by 32
A new tool for studying protein structure and function
Cornish, V. W., & Schultz, P. G. (1994) · Current Opinion in Structural Biology · doi:10.1016/s0959-440x(94)90224-0 · Cited by 30
Deming, T. J., Fournier, M. J., Mason, T. L., & Tirrell, D. A. (1997) · Journal of Macromolecular Science Part A · doi:10.1080/10601329708010331 · Cited by 30
Self-citationBentin, T., Hamzavi, R., Salomonsson, J., Roy, H., Ibba, M., & Nielsen, P. E. (2004) · Journal of Biological Chemistry · doi:10.1074/jbc.m401278200 · Cited by 28
Crystallographic Evidence for Isomeric Chromophores in 3‐Fluorotyrosyl‐Green Fluorescent Protein
Bae, J. H., Pal, P. P., Moroder, L., Huber, R., & Budiša, N. (2004) · ChemBioChem · doi:10.1002/cbic.200300818 · Cited by 26
Sisido, M., Ninomiya, K., Ohtsuki, T., & Hohsaka, T. (2005) · Methods · doi:10.1016/j.ymeth.2005.04.009 · Cited by 26
OPTICAL PROPERTIES OF FUNCTIONALIZED POLYTHIOPHENES
Somanathan, N., & Radhakrishnan, S. (2005) · International Journal of Modern Physics B · doi:10.1142/s0217979205032930 · Cited by 26
Mock, M. L., Michon, T., van Hest, J. C. M., & Tirrell, D. A. (2006) · ChemBioChem · doi:10.1002/cbic.200500201 · Cited by 23
Self-citationSynthesis and incorporation of [6,7]-selenatryptophan into dihydrofolate reductase
Boles, J. O., Henderson, J. A., Hatch, D. M., & Silks, L. A. (2002) · Biochemical and Biophysical Research Communications · doi:10.1016/s0006-291x(02)02438-5 · Cited by 16
Sando, S., Kanatani, K., Sato, N., Matsumoto, H., Hohsaka, T., & Aoyama, Y. (2005) · Journal of the American Chemical Society · doi:10.1021/ja0502977 · Cited by 9
Rostovtsev, V. V., Green, L. G., Fokin, V. V., & Sharpless, K. B. (2002) · Angewandte Chemie International Edition · doi:10.1002/1521-3773(20020715)41:14
Research works printed but not linked: 1
- Pratt E. A., 1974, Fed. Proc., 33, 1463
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Alconcel, S. N. S., Baas, A. S., & Maynard, H. D. (2011) · Polymer Chemistry · doi:10.1039/c1py00034a · Cited by 658
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Metadata
- Authors
- Connor, R. E., & Tirrell, D. A.
- Affiliations
- California Institute of Technology (US)
- Corresponding author
- Tirrell, David A.
- Venue
- Polymer Reviews
- Publisher
- Informa UK Limited
- Published
- 2007-04
- Volume
- 47
- Issue
- 1
- Pages
- 9-28
- ISSN
- 0736-6574 (ISSN-L)
- 1558-3724
- 1558-3716
- OpenAlex
- W1981527166
- Cited by
- 103
- References
- 92
- Citations by year
- 2025: 3 · 2024: 3 · 2023: 3 · 2022: 6 · 2021: 3 · 2020: 3 · 2019: 5 · 2018: 1 · 2017: 4 · 2016: 4 · 2015: 2 · 2014: 5 · 2013: 10 · 2012: 9
- FWCI
- 3.95
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of macromolecular science. Part C, Reviews in macromolecular chemistry and physics/Journal of macromolecular science. Reviews in macromolecular chemistry and physics (publishedVersion)
- CaltechAUTHORS (California Institute of Technology) (submittedVersion)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › RNA and protein synthesis mechanisms
- Physical Sciences › Chemistry › Organic Chemistry › Chemical Synthesis and Analysis
- Physical Sciences › Chemistry › Organic Chemistry › Click Chemistry and Applications
- Keywords
- unnatural amino acids, protein polymers, engineered proteins, biosensors, biomaterials
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