Non-enzymatic glycation of phosphoglucoisomerase.

Incubation of yeast phosphoglucoisomerase for 14 days at a high concentration (100 mM) of D-glucose was found to cause the non-enzymatic glycation of the enzyme. The kinetic properties of the glycated and control enzymes were similar in terms of specific activity, affinity for D-glucose 6-phosphate, isotopic discrimination between D-(U-14C) glucose 6-phosphate and D-(2-3H) glucose 6-phosphate, intramolecular 3H transfer from the latter substrate, and anomeric specificity. It is proposed that the quantitation of glycated phosphoglucoisomerase in distinct cell types may be used as an index for the non-enzymatic glycation of cytosolic proteins.