IS THE INCREASE IN AGE-PROTEINS IN UREMIA THE RESULT OF OXIDATIVE STRESS OR CARBONYL STRESS?
In addition to oxidative chemistry, nonoxidative pathways also contribute to the formation of reactive carbonyl compounds. For example, 3-deoxyglucosone is formed nonoxidatively by rearrangement and decomposition of Amadori compounds45 or by anaerobic metabolic reactions leading to the formation of fructose-3-phosphate, which decomposes spontaneously to 3-deoxyglucosone46. The more reactive dicarbonyl compound methylglyoxal, formed by oxidative decomposition of polyunsaturated fatty acids47, is also formed during anaerobic glycolysis by spontaneous decomposition of triose phosphates and during anaerobic metabolism of acetone and amino acids48. Both 3-deoxyglucosone and methylglyoxal react with protein amino groups and form AGEs on proteins. The increase in 3-deoxyglucosone and its protein adducts in uremic serum49 is evidence of the contribution of nonoxidative chemistry to the formation of reactive carbonyl compounds and AGEs in uremia. Although the levels of glyoxal and methylglyoxal
