Endogenous Glyoxal

endogenous glyoxal

Glyoxal is endogenously produced during normal cellular metabolism by a multitude of enzyme-independent pathways, such as the spontaneous reaction of amino groups in proteins with reducing sugars, sugar autoxidation, DNA oxidation, peroxidation of polyunsaturated fatty acids, and UV photodamage, and in conditions of oxidative stress and depletion of GSH.

Furthermore, glyoxal is a product of the metabolism and microsomal oxidation of compounds such as glycolaldehyde, ethylene glycol, and beta-hydroxy-substituted N-nitrosamines and possibly contributes to the toxic, genotoxic, and tumorigenic action of these substances.

glyoxal appearance

In biological materials, less than 10% of the glyoxal present is in unbound forms in aqueous solution (free glyoxal and hydrates), as most of the reactive carbonyl groups are reversibly bound to cysteinyl, lysyl, and arginyl residues of proteins.

The endogenous concentrations of glyoxal in human tissues and body fluids, as with other alpha-oxoaldehydes, are limited by the high catalytic efficiency of the glyoxalase system as well as by the rapid reaction of glyoxal with proteins.

During certain pathological conditions (e.g., diabetes mellitus, uraemia), raised concentrations of glyoxal have been measured. The concentration of glyoxal in blood samples from normal human subjects (n = 19) was 0.21 ± 0.14 µmol/kg. For blood plasma, a value of approximately 0.1 µmol/litre was estimated for normal healthy subjects, which can double in diabetics.

 

 

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