Activated and unactivated forms of human erythrocyte aldose reductase

S. K. Srivastava, G. A. Hair, B. Das

Research output: Contribution to journalArticle

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Abstract

Aldose reductase (alditol:NADP+ 1-oxidoreductase, EC 1.1.1.21) has been partially purified from human erythrocytes by DEAE-cellulose (DE-52) column chromatography. This enzyme is activated severalfold upon incubation with 10 μM each glucose 6-phosphate, NADPH, and glucose. The activation of the enzyme was confirmed by following the oxidation of NADHP as well as the formation of sorbitol with glucose as substrate. The activated form of aldose reductase exhibited monophasic kinetics with both glyceraldehyde and glucose (K(m) of glucose = 0.68 mM and K(m) of glyderaldehyde = 0.096 mM), whereas the native (unactivated) enzyme exhibited biphasic kinetics (K(m) of glucose = 9.0 and 0.9 mM and K(m) of glyceraldehyde = 1.1 and 0.14 mM). The unactivated enzyme was strongly inhibited by aldose reductase inhibitors such as sorbinil, alrestatin, and quercetrin, and by phosphorylated intermediates such as ADP, glycerate 3-phosphate, glycerate 1,3-bisphosphate, and glycerate 2,3-trisphosphate. The activated form of the enzyme was less susceptible to inhibition by aldose reductase inhibitors and phosphorylated intermediates.

Original languageEnglish (US)
Pages (from-to)7222-7226
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume82
Issue number21
DOIs
StatePublished - 1985

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