title: Preparation and photophysical properties of a caged kynurenine.
abstract: We have prepared l-kyurenine 4-hydroxyphenacyl ester, a caged derivative of L-kynurenine. N(α)-tBOC-L-tryptophan was reacted with 4-hydroxyphenacyl bromide in DMF with K(2)CO(3) as the base to give the N(α)-tBOC 4-hydroxyphenacyl ester. The ester was then treated with O(3) in MeOH at -20°C, followed by trifluoroacetic acid in CH(2)Cl(2), then aqueous HCl to obtain the caged kynurenine as the dihydrochloride salt. The caged kynurenine is stable as a dry solid in the dark at -78°C, but in aqueous solutions in phosphate buffer at pH 7-8 hydrolyzes rapidly (t(1/2) ∼5 min). Solutions in Tris at pH 7 are more stable (t(1/2) >30 min), and solutions in 1mM HCl are stable for several hours. As expected, the ester is cleaved in microseconds with laser pulses at 355 nm. The caged kynurenine may be useful for preparation of substrate complexes for crystallography or in biological studies on kynurenine.
authors.affiliation: Department of Chemistry, University of Georgia, Athens, GA 30602, USA.
authors.forename: Chandan
authors.initials: C
authors.lastname: Maitrani
authors.forename: Derren J
authors.initials: DJ
authors.lastname: Heyes
authors.forename: Sam
authors.initials: S
authors.lastname: Hay
authors.forename: Selvanathan
authors.initials: S
authors.lastname: Arumugam
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Popik
authors.forename: Robert S
authors.initials: RS
authors.lastname: Phillips
mesh_terms: D000098:Acetophenones / Q000737:chemistry; D007737:Kynurenine / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry*; D007834:Lasers; D015394:Molecular Structure
chemical_list: C465291:4-hydroxyphenacyl bromide; D000098:Acetophenones; C574925:L-kynurenine 4-hydroxyphenacyl ester; D007737:Kynurenine