The effect of non-enzymatic glycation on recombinant human aldose reductase.
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 non-enzymatically glycated with HPLC-purified [3H]D-glucose, the Michaelis constant (Km) and catalytic efficiency (Kcat/Km) for glyceraldehyde, the Km for NADPH and the inhibitor constant (Ki) 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.
Yamaoka
T
T
Division of Endocrinology and Metabolism, University of Tsukuba, Ibaraki, Japan.
Oda
A
A
Bannai
C
C
Itakura
M
M
Yamashita
K
K
D000449:Aldehyde Reductase / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D005449:Fluorenes / Q000378:metabolism / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D006827:Hydantoins / Q000378:metabolism / Q000494:pharmacology; D007093:Imidazoles / Q000378:metabolism / Q000494:pharmacology; D048289:Imidazolidines; D007700:Kinetics; D009281:Naphthalenes / Q000378:metabolism / Q000494:pharmacology; D010793:Phthalazines / Q000378:metabolism / Q000494:pharmacology; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism; D013379:Substrate Specificity; D014162:Transfection
D004791:Enzyme Inhibitors; D005449:Fluorenes; D006827:Hydantoins; D007093:Imidazoles; D048289:Imidazolidines; D009281:Naphthalenes; D010793:Phthalazines; D011994:Recombinant Proteins; C052241:imirestat; C040550:tolrestat; C042829:ponalrestat; D000449:Aldehyde Reductase; C026411:sorbinil; D005947:Glucose