Carbonyl compounds protein modification

Pyridoxamine is a potent inhibitor of the irreversible rearrangement of the initial product of reversible glycation to the advanced glycation end-product. Such inhibitors of this reaction are collectively known as amadorins, and the name pyridorin has been coined for pyridoxamine used in this way (KhaUfah et al., 1999). Pyridoxamine also inhibits protein modification caused by lipid peroxides in both cases, it seems to act by trapping carbonyl compounds formed as intermediates (Onorato et al., 2000 Voziyan et al., 2002). 

In a somewhat different interpretation of available data, Baynes and Thorpe (1999) have stressed the importance of the formation in diabetic tissues of reactive carbonyl compounds, produced by either metabolic or nonenzymatic processes that may or may not require oxygen. The excess of reactive carbonyls is proposed to then promote glycoxidation and lipoxidation so as to cause chemical modification of proteins. These... 

There is increased reactive carbonyl compound (RCO) with attendant protein modification (carbonyl stress) in atherosclerosis carbonyl stress might be derived from hyperglycemia (and lipedemia), oxidative stress, and/or impaired detoxification of RCO (423). 

Unfortunately, there are no universal methods to detect all types of protein oxidation, because the products formed can be so diverse in nature. However, some forms of protein oxidation can be assayed using chemical modification (Davies et al., 1999 Shacter, 2000). In particular, the formation of carbonyl groups on proteins can be targeted using the reagent 2,4-dinitrophenyl-hydrazine (DNPH). This compound reacts with aldehydes to form 2,4-dinitrophenylhydrazone derivatives, which create chromogenic modifications that can be detected at high sensitivity in microplate assays or Western blot analysis (Buss et al., 1997 Winterbourn et al., 1999). 

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