title: Inhibition of ascorbic acid-induced modifications in lens proteins by peptides.
abstract: The effects of three dipeptides L-phenylalanyl-glybine, glycyl-L-phenylalanine,and aspartame (L-aspartyl-L-phenylalanine, methyl ester) as inhibitors of the ascorbic acid-induced modifications in lens proteins were studied. Their efficiency was compared to that of two known inhibitors--aminoguanidine and carnosine. The tested dipeptides diminished protein carbonyl content by 32-58% and most moderated the formation of chromophores, as measured by the absorbency at 325 nm of the glycated proteins. The appearance of non-tryptophan fluorescence (excitation 340 nm/emission 410 nm) was observed for proteins glycated with ascorbic acid. All of the dipeptides examined, as well as aminoguanidine, decreased this glycation-related fluorescence. The potential inhibitors prevented the intensive formation of very high molecular weight aggregates. A competitive mechanism of their inhibitory effect was proposed, based on the reactivity of individual substances toward ascorbic acid. These findings indicate that they have a potential for use as alternatives for aminoguanidine as an anti-glycation agent.
authors.affiliation: Department of Chemistry and Biochemistry. Medical Institute, 15a Vassil Aprilov St, 4002 Plovdiv, Bulgaria. margirova@hotmail.com
authors.forename: Mariana
authors.initials: M
authors.lastname: Argirova
authors.forename: Ognyan
authors.initials: O
authors.lastname: Argirov
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D002417:Cattle; D003432:Cross-Linking Reagents; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000378:metabolism*; D005453:Fluorescence; D006031:Glycosylation / Q000187:drug effects; D007908:Lens, Crystalline / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D010084:Oxidation-Reduction / Q000187:drug effects; D010455:Peptides / Q000494:pharmacology*; D013056:Spectrophotometry, Ultraviolet; D014443:Tyrosine / Q000378:metabolism
chemical_list: D003432:Cross-Linking Reagents; D005136:Eye Proteins; D010455:Peptides; D014443:Tyrosine; D001205:Ascorbic Acid