GENERATION OF PROTEIN CARBONYLS BY GLYCOXIDATION AND LIPOXIDATION REACTIONS WITH AUTOXIDATION PRODUCTS OF ASCORBIC-ACID AND POLYUNSATURATEDFATTY-ACIDS

Accumulation of carbonyl derivatives of proteins (protein carbonyl) is taken as a biomarker of oxidative protein damage in aging and in vari ous diseases. We detected protein carbonyls in situ in human diabetic arteriosclerotic tissues and characterized the formation of protein ca rbonyls, Protein carbonyls were identified in the thickened intima of arterial walls and co-localized with protein adducts formed by carbony l amine chemistry between protein and carbonyl compounds derived from autoxidation of carbohydrates, lipids, and ascorbate, i,e, advanced gl ycation end products or glycoxidation products, such as carboxymethyll ysine (CML) and pentosidine, and lipoxidation products, such as malond ialdehyde (MDA) and 4-hydroxy-nonenal (HNE). In vitro incubation of pr oteins with ascorbic acid accelerated the production of protein carbon yls as well as CML and pentosidine, and incubation with arachidonate a ccelerated the production of protein carbonyls as web as CML, MDA, and HNE, By contrast, incubation of proteins with glucose resulted in the production of CML and pentosidine, but not protein carbonyls, Schiff base inhibitors, lidenehydrazono-4-oxo-thiazolidino-4-ylacetanilide an d aminoguanidine, inhibited the production of protein carbonyls after incubation with ascorbate and arachidonate, The present study suggests that ascorbate and polyunsaturated fatty acids, but not glucose, repr esent potential sources of protein carbonyls, and that both the glycox idation and lipoxidation reactions contribute to protein carbonyl form ation in aging and various diseases, (C) 1998 Federation of European B iochemical Societies.