Chemistry:Azidophenylalanine
Azidophenylalanine (4-azido-L-phenylalanine) is an unnatural amino acid derivative of L-phenylalanine, featuring an azide group at the para position of the phenyl ring. It is a bioorthogonal click-chemistry reagent that can be genetically incorporated into proteins via expanded genetic code techniques for site-specific labeling and functionalization.[1] The compound serves as a vibrational reporter for local protein environments due to its azide group[2] and is used in photo-crosslinking for protein interaction studies.[3]
Chemical properties
Azidophenylalanine has the molecular formula C
9H
10N
4O
2 and a molecular weight of 206.20 g/mol.[4] Its IUPAC name is (2S)-2-amino-3-(4-azidophenyl)propanoic acid. It appears as an off-white solid and is soluble in water, DMSO, and DMF.[5]
As with many other azides, the isolated compound exhibits explosive properties.[5][6] It is light-sensitive and should be stored at -20 °C in the dark.
Synthesis
A chromatography-free synthesis of azidophenylalanine has been reported. It starts from L-phenylalanine and includes iodination to form 4-iodo-L-phenylalanine, followed by Boc protection, Cu(I)-catalyzed azidation using sodium azide (NaN3), deprotection with sulfuric acid, and purification by recrystallization.[5] This method avoids explosion risks associated with earlier approaches.
Research uses
As an analog of L-phenylalanine, azidophenylalanine is incorporated into proteins during translation in place of phenylalanine.[7] The azide group enables bioorthogonal reactions, such as copper-catalyzed or strain-promoted azide-alkyne cycloadditions, for protein modification.
Azidophenylalanine is employed in metabolic labeling to detect nascent protein synthesis as a non-radioactive alternative to traditional methods. It facilitates site-specific protein labeling for microscopic imaging, purification, and FRET studies. Applications include photochemical control of fluorescent proteins, synthesis of ligands for metal complexation in EPR/NMR, and probing protein dynamics during folding or catalysis. It is incorporated using orthogonal tRNA/synthetase pairs in systems like E. coli.[7]
References
- ↑ Ma, Xiaofeng; Wei, Bing; Wang, Enlin (2022). "Efficient incorporation of p-azido-l-phenylalanine into the protein using organic solvents". Protein Expression and Purification 200. doi:10.1016/j.pep.2022.106158. PMID 36007861.
- ↑ Löffler, Jan G.; Deniz, Erhan; Feid, Carolin; Franz, Valentin G.; Bredenbeck, Jens (2022). "Versatile Vibrational Energy Sensors for Proteins". Angewandte Chemie International Edition 61 (21). doi:10.1002/anie.202200648. PMID 35226765. Bibcode: 2022ACIE...61E0648L.
- ↑ Schwyzer, Robert; Caviezel, Mario (1971). "p -Azido-L-phenylalanine: A photo-affinity 'probe' related to tyrosine". Helvetica Chimica Acta 54 (5): 1395–1400. doi:10.1002/hlca.19710540521. PMID 5121750.
- ↑ CID 3080772 from PubChem
- ↑ 5.0 5.1 5.2 Richardson, Mark B.; Brown, Derek B.; Vasquez, Carlos A.; Ziller, Joseph W.; Johnston, Kevin M.; Weiss, Gregory A. (2018). "Synthesis and Explosion Hazards of 4-Azido- l -phenylalanine". The Journal of Organic Chemistry 83 (8): 4525–4536. doi:10.1021/acs.joc.8b00270. PMID 29577718.
- ↑ Derek Lowe. "4-Azidophenylalanine: A Warning". In the Pipeline. Science. https://www.science.org/content/blog-post/4-azidophenylalanine-warning.
- ↑ 7.0 7.1 Chin, Jason W.; Santoro, Stephen W.; Martin, Andrew B.; King, David S.; Wang, Lei; Schultz, Peter G. (2002). "Addition of p -Azido-l-phenylalanine to the Genetic Code of Escherichia c oli". Journal of the American Chemical Society 124 (31): 9026–9027. doi:10.1021/ja027007w. PMID 12148987. Bibcode: 2002JAChS.124.9026C.
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