title: A photoactivable amino acid based on a novel functional coumarin-6-yl-alanine.
abstract: A novel fluorescent amino acid, L-4-chloromethylcoumarin-6-yl-alanine, was obtained from tyrosine by a Pechmann reaction. The assembly of the heterocyclic ring at the tyrosine side chain could be achieved before or after incorporation of tyrosine into a dipeptide, and amino acid and dipeptide ester conjugates were obtained by coupling to a model N-protected alanine. The behaviour of one of the fluorescent conjugates towards irradiation was studied in a photochemical reactor at different wavelengths (254, 300, 350 and 419 nm). The photoreaction course in methanol/HEPES buffer solution (80:20) was followed by HPLC/UV monitoring. It was found that the novel unnatural amino acid could act as a fluorescent label, due to its fluorescence properties, and, more importantly, as a photoactivable unit, due to the short irradiation times necessary to cleave the ester bond between the model amino acid and the coumarin-6-yl-alanine.
authors.affiliation: Centro de Química, Universidade do Minho, Campus de Gualtar, 4710-057, Braga, Portugal.
authors.forename: Andrea S C
authors.initials: AS
authors.lastname: Fonseca
authors.forename: M Sameiro T
authors.initials: MS
authors.lastname: Gonçalves
authors.forename: Susana P G
authors.initials: SP
authors.lastname: Costa
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D003374:Coumarins / Q000138:chemical synthesis / Q000737:chemistry*; D005453:Fluorescence; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D055668:Photochemical Processes; D013050:Spectrometry, Fluorescence; D014443:Tyrosine / Q000737:chemistry*
chemical_list: C581094:4-chloromethylcoumarin-6-ylalanine; D003374:Coumarins; D014443:Tyrosine; D000409:Alanine