Kinetic and Structural Characterization of the Glutathione-binding Site of Aldose Reductase

Abstract

Aldose reductase (AR), a member of the aldo-keto reductase superfamily, has been implicated in the etiology of secondary diabetic complications. However, the physiological functions of AR under euglycemic conditions remain unclear. We have recently demonstrated that, in intact heart, AR catalyzes the reduction of the glutathione conjugate of the lipid peroxidation product 4-hydroxy-trans-2-nonenal (Srivastava, S., Chandra, A., Wang, L., Seifert, W. E., Jr., DaGue, B. B., Ansari, N. H., Srivastava, S. K., and Bhatnagar, A. (1998) J. Biol. Chem. 273, 10893-10900), consistent with a possible role of AR in the metabolism of glutathione conjugates of aldehydes. Herein, we present several lines of evidence suggesting that the active site of AR forms a specific glutathione-binding domain. The catalytic efficiency of AR in the reduction of the glutathione conjugates of acrolein, trans-2-hexenal, trans-2-nonenal, and trans,trans-2,4-decadienal was 4 -1000-fold higher than for the corresponding free alkanal. Alterations in the structure of glutathione diminished the catalytic efficiency in the reduction of the acrolein adduct, consistent with the presence of specific interactions between the amino acid residues of glutathione and the AR active site. In addition, non-aldehydic conjugates of glutathione or glutathione analogs displayed active-site inhibition. Molecular dynamics calculations suggest that the conjugate adopts a specific low energy configuration at the active site, indicating selective binding. These observations support an important role of AR in the metabolism of glutathione conjugates of endogenous and xenobiotic aldehydes and demonstrate, for the first time, efficient binding of glutathione conjugates to an aldo-keto reductase.

Role of Aldose Reductase in the Metabolism and Detoxification of Carnosine-Acrolein Conjugates

“…This conjugative reaction is further enhanced by glutathione S-transferases. Our previous studies have shown that the glutathione conjugates of aldehydes are further metabolized by a reductive transformation catalyzed by aldose reductase (AR) (17,18) and that inhibition of this metabolic transformation increases aldehyde accumulation and exacerbates ischemic injury (19) and atherosclerotic lesion formation (6). These observations support the view that reduction diminishes the ability of aldehyde-glutathione conjugates to induce tissue toxicity.…”

Aldose Reductase Mediates Mitogenic Signaling in Vascular Smooth Muscle Cells

“…As a result, AR does not display predominant specificity for a unique substrate-product pair; rather, it can reduce several types of aldehydes with nearly equal efficiency. Such behavior confers ideal properties to AR for the reduction of multiple aldehydes, such as the aldo-keto sugars and the aldehydes generated by lipid peroxidation (3)(4)(5)(6)(7)(8). The broad substrate specificity of the enzyme precludes its ready implication in a unique metabolic pathway and suggests that it may be recruited for tissue-specific use under a variety of metabolic contexts.…”

“…The reduction of glucose by AR is particularly significant during hyperglycemia, and increased flux of glucose via AR has been etiologically linked to the development of secondary diabetic complications (1,2). However, recent studies showing that AR is an excellent catalyst for the reduction of lipid peroxidation-derived aldehydes and their glutathione conjugates (3)(4)(5)(6)(7)(8) suggest that in contrast to its injurious role during diabetes, under normal glucose concentration, AR may be involved in protection against oxidative and electrophilic stress. The antioxidant role of AR is consistent with the observations that in a variety of cell types AR is up-regulated by oxidants such as hydrogen peroxide (9), lipid peroxidation-derived aldehydes (10,11), advanced glcosylation end products (12), and nitric oxide (13).…”

Intracellular Metabolism of α,β-Unsaturated Carbonyl Compounds, Acrolein, Crotonaldehyde and Methyl Vinyl Ketone, Active Toxicants in Cigarette Smoke: Participation of Glutathione Conjugation Ability and Aldehyde–Ketone Sensitive Reductase Activity

“…This enzyme catalyzes the reduction of GSH conjugates of α,β-unsaturated aldehydes with higher catalytic efficiency than free aldehydes. 24,25) The aldo-keto reductase family 1 member B10 is an important protein protecting the host cell against α,β-unsaturated carbonyls and their GSH-conjugates. 22) Shen et al 26) have reported that aldo-keto reductase family 1 member B1 efficiently reduces GSH-conjugated carbonyl compounds and plays an important role in the detoxification of their compounds.…”