title: Experimental parameters affecting the ultraviolet-induced tryptophan modification in the lens.
abstract: Experimental parameters affecting photolysis of tryptophan in the lens were evaluated, including: (a) the use of previously-frozen vs. freshly excised lenses, (b) the use of lenses in aqueous buffered solutions vs. in air, (c) the species source of the lens, and (d) the effects of oxygen depletion. Lenses were subjected to monochromatic ultraviolet radiation followed by monitoring of the tryptophan fluorescence spectra while exciting at two or more wavelengths. Previously frozen lenses showed faster UV-induced degradation of tryptophan, particularly in aqueous media. A rapid leakage of fluorescent components (including amino acids and peptides) from intact lenses was observed. Evidence for the artifactual production of free radicals during photometric monitoring of samples in solution was obtained. Species dependent differences were also observed.
authors.affiliation: Department of Biochemistry, University of North Texas, Texas College of Osteopathic Medicine, Fort Worth 76107.
authors.forename: J M
authors.initials: JM
authors.lastname: Talent
authors.forename: L F
authors.initials: LF
authors.lastname: Peng
authors.forename: R W
authors.initials: RW
authors.lastname: Gracy
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002417:Cattle; D004285:Dogs; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D005615:Freezing; D007908:Lens, Crystalline / Q000528:radiation effects*; D011817:Rabbits; D051381:Rats; D013045:Species Specificity; D013057:Spectrum Analysis; D014364:Tryptophan / Q000378:metabolism* / Q000528:radiation effects; D014466:Ultraviolet Rays; D014867:Water
chemical_list: D000596:Amino Acids; D005609:Free Radicals; D014867:Water; D014364:Tryptophan