Arginine with glyoxals

T. Hofmann, 4-Alkylidene-2-imino-5-[4-alkylidene-5-oxo-l,3-imidazol-2-inyl]aza-methylidine-l,3-imidazolidine —A novel colored substructure in melanoidins formed by Maillard reactions of bound arginine with glyoxal and furan-2-carboxaldehyde, J. Agric. Food Chem., 1998, 46, 3896-3901. 

Much attention has recently been paid to arginine as a melanoidin precursor. In a model system, lV -acetylarginine was first allowed to react with glyoxal in aqueous solution at pH 7, followed by furfural. Repeated chromatography of the aqueous residue after ethyl acetate extraction led to a 1% yield of the deep red 29.180 Such a compound provides an example of a potentially coloured crosslink in proteins derived by the Maillard reaction (see Chapter 8). 

The reaction of dicarbonyl compounds, such as glyoxal or phenylglyoxal, with a guanidinyl group, such as that of an arginine residue, proceeds to yield a more stable linkage due to the formation of a cyclic derivative (Reaction 46). 

U. Schwarzenbolz, T. Henle, and H. Klostermeyer, Studies on the reaction of glyoxal with protein-bound arginine, in F, 1998, 443. 

Imidazolone adducts formed by reaction of 3-deoxyglucosone or methylglyoxal with arginine and the imidazolium cross-links formed by the reaction of glyoxal and methylglyoxal with lysine residues in protein are also considered as biomarkers of protein oxidative damage (08). 

Transamination of glyoxalate takes place with several amino acid donors glycine, glutamate, ornithine, arginine, and methionine. 

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