The effect of non-enzymatic glycation on recombinant human aldose reductase

Abstract It has been demonstrated that activation of aldose reductase (AR; EC 1.1.1.21) in diabetic tissues plays an important role in the pathogenesis of diabetic complications. In the present study, the effects of non-enzymatic glycation of recombinant human AR (rhAR) on enzyme activity and affinity for its substrate (glyceraldehyde), co-factor (NADPH) and inhibitors (ARI; Sorbinil, Tolrestat, AL-1576 and Statil) were examined. Although rhAR was successfully nonenzymatically glycated with HPLC-purified [ 3 H] d -glucose, the Michaelis constant ( K m ) and catalytic efficiency ( K cat K m ) for glyceraldehyde, the K m for NADPH and the inhibitor constant ( K i ) for ARI did not change. These results suggest that the mechanism of AR activation and its insensitivity to inhibition observed in diabetic tissues cannot be attributed to its non-enzymatic glycation.