Susceptibility of gamma-irradiated proteins to in vitro glycation: exposure to oxygen free radicals increases glycation-induced modifications.
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.
Traverso
N
N
Institute of General Pathology, University of Genoa, Italy.
Odetti
P
P
Cheeseman
K
K
Cottalasso
D
D
Marinari
U M
UM
Pronzato
M A
MA
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
D005456:Fluorescent Dyes; D005609:Free Radicals; D017382:Reactive Oxygen Species; D012710:Serum Albumin, Bovine; D014364:Tryptophan; D005947:Glucose