title: Susceptibility of gamma-irradiated proteins to in vitro glycation: exposure to oxygen free radicals increases glycation-induced modifications.
abstract: Oxidation and glycation are non-enzymatic protein modifications involved in the pathogenesis of aging. We evaluated their possible influences in an in vitro system: albumin was oxidized by gamma-irradiation and then exposed to glycation in vitro. Fluorescence modifications were analysed as signals of protein alterations. Both radiolytic oxidation and in vitro glycation provoked a sharp decrease of tryptophan fluorescence (278 nm ex./340 nm em.); their effects tended to be additive, unless a saturation limit was reached. Both individually and in combination, these two non-enzymatic processes induced the appearance of a new fluorescence (335 nm ex./415 nm em.); in this case as well there was an additive effect, with a trend toward saturation. Radiolytic oxidation and in vitro glycation seem to provoke similar damage to the exposed proteins: the observed fluorescence alterations may be due to similar conformational changes, breaks or the development of fluorophores.
authors.affiliation: Institute of General Pathology, University of Genoa, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Traverso
authors.forename: P
authors.initials: P
authors.lastname: Odetti
authors.forename: K
authors.initials: K
authors.lastname: Cheeseman
authors.forename: D
authors.initials: D
authors.lastname: Cottalasso
authors.forename: U M
authors.initials: UM
authors.lastname: Marinari
authors.forename: M A
authors.initials: MA
authors.lastname: Pronzato
mesh_terms: D000375:Aging / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D005456:Fluorescent Dyes; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D005720:Gamma Rays; D005947:Glucose / Q000737:chemistry / Q000378:metabolism; D006031:Glycosylation; D010084:Oxidation-Reduction; D011487:Protein Conformation; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*; D014364:Tryptophan / Q000737:chemistry / Q000528:radiation effects
chemical_list: D005456:Fluorescent Dyes; D005609:Free Radicals; D017382:Reactive Oxygen Species; D012710:Serum Albumin, Bovine; D014364:Tryptophan; D005947:Glucose