Stereoselectivity of Aldose Reductase in the Reduction of Glutathionyl-Hydroxynonanal Adduct

Abstract

The formation of the adduct between the lipid peroxidation product 4-hydroxy-2-nonenal (HNE) and glutathione, which leads to the generation of 3-glutathionyl-4-hydroxynonane (GSHNE), is one of the main routes of HNE detoxification. The aldo-keto reductase AKR1B1 is involved in the reduction of the aldehydic group of both HNE and GSHNE. In the present study, the effect of chirality on the recognition by aldose reductase of HNE and GSHNE was evaluated. AKR1B1 discriminates very modestly between the two possible enantiomers of HNE as substrates. Conversely, a combined kinetic analysis of the glutathionyl adducts obtained starting from either 4R- or 4S-HNE and mass spectrometry analysis of GSHNE products obtained from racemic HNE revealed that AKR1B1 possesses a marked preference toward the 3S,4R-GSHNE diastereoisomer. Density functional theory and molecular modeling studies revealed that this diastereoisomer, besides having a higher tendency to be in an open aldehydic form (the one recognized by AKR1B1) in solution than other GSHNE diastereoisomers, is further stabilized in its open form by a specific interaction with the enzyme active site. The relevance of this stereospecificity to the final metabolic fate of GSHNE is discussed.

Models of enzyme inhibition and apparent dissociation constants from kinetic analysis to study the differential inhibition of aldose reductase

“…EGCG, NADPH and L-idose were obtained from Carbosynth (Compton, England). HNE and 3-glutathionyl-4-hydroxynonanal (GSHNE) were synthesised as described 25 . All other chemicals were of a reagent grade.…”

Pathways of 4-Hydroxy-2-Nonenal Detoxification in a Human Astrocytoma Cell Line

“…HNE was synthesized as previously described [30]. GSHNE was synthesized as described [32]. NADP + , NAD + , NADPH and NADH were from Carbosynth (Compton, England).…”

Aldose Reductase Differential Inhibitors in Green Tea

“…GSHNE exists as four different diastereoisomers that behave differently as AKR1B1 substrates. In particular, the diastereoisomer couple 3R/S,4R-GSHNE displays more favorable kinetic parameters with respect to the diastereoisomer couple 3R/S,4S-GSHNE with an approximately 20 times higher specificity constant [69].…”

“…The analysis performed with 3R,4R-GSHNE produced different results [69]. In this case, one of the 12 suitable complexes generated by docking and analyzed through MD simulations (complex 3) was found to outperform all the others from both a qualitative and quantitative point of view, showing a binding energy of −30.0 kcal/mol and an average RMSD of ligand disposition of 1.9 Å (Table S2).…”