The formation of methylglyoxal from triose phosphates

Abstract

In Krebs-Ringer phosphate buffer, the rate of formation of methylglyoxal from glycerone phosphate and glyceraldehyde 3-phosphate was first order with respect to the triose phosphate with rates constant values of 1.94 ± 0.02 × 10⁻⁵ s⁻¹ (n= 18) and 1.54 ± 0.02 × 10⁻⁴ s⁻¹ (n= 18) at 37°C, respectively. The rate of formation of methylglyoxal from glycerone phosphate and glyceraldehyde 3-phosphate in the presence of red blood cell lysate was not significantly different from the nonenzymatic value (P > 0.05). Methylglyoxal formation from glycerone phosphate was increased in the presence of triose phosphate isomerase but this may be due to the faster non-enzymatic formation from the glyceraldehyde 3-phosphate isomerisation product. For red blood cells in vitro, the predicted non-enzymatic rate of formation of methylglyoxal from glycerone phosphate and glyceraldehyde 3-phosphate may account for the metabolic flux through the glyoxalase system. The reactivity of glycerone phosphate and glyceraldehyde 3-phosphate towards the non-enzymatic formation of methylglyoxal under physiological conditions suggests that methylglyoxal formation is unavoidable from the Embden-Meyerhof pathway.