The formation of methylglyoxal from triose phosphates. Investigation using a specific assay for methylglyoxal.
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 x 10(-5) s-1 (n = 18) and 1.54 +/- 0.02 x 10(-4) s-1 (n = 18) at 37 degrees 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 non-enzymatic 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.
Phillips
S A
SA
Department of Chemistry and Biological Chemistry, University of Essex, Colchester, England.
Thornalley
P J
PJ
D004099:Dihydroxyacetone Phosphate / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism; D005986:Glyceraldehyde 3-Phosphate / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D011765:Pyruvaldehyde / Q000378:metabolism*; D014305:Triose-Phosphate Isomerase / Q000494:pharmacology
D005986:Glyceraldehyde 3-Phosphate; D004099:Dihydroxyacetone Phosphate; D011765:Pyruvaldehyde; D014305:Triose-Phosphate Isomerase