CCDC 1476501: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures

A facile synthesis of 2-(4-((4-chlorophenyl)(hydroxy)methyl) phenoxy)-2-methylpropanoic acid: Metabolite of anti-hyperlipidemic drug Fenofibrate

Synthesis and characterization of drug metabolites has emerged as an important area of research in consideration to the significant contribution of studies on metabolites in drug research. The present work comprises synthesis of 2-(4-((4-chlorophenyl)(hydroxy)methyl) phenoxy)-2-methylpropanoic acid, a metabolite of anti-hyperlipidemic drug fenofibrate. The desired compound was prepared by two different synthetic routes. The ketone group of fenofibric acid was reduced using sodium borohydride in one route whereas the hydrolysis of isopropyl ester of the reduced fenofibrate was achieved by the mild alkaline hydrolysis in the other path. Both the ways of synthesis furnished the desired compound in excellent yield and purity. The new synthetic congener was characterized by spectroscopic methods

Characterization of WY 14,643 and its complex with Aldose reductase

The peroxisome proliferator, WY 14,643 exhibits a pure non-competitive inhibition pattern in the aldehyde reduction and in alcohol oxidation activities of human Aldose reductase (hAR). Fluorescence emission measurements of the equilibrium dissociation constants, Kd, of oxidized (hAR•NADP+) and reduced (hAR•NADPH) holoenzyme complexes display a 2-fold difference between them. Kd values for the dissociation of WY 14,643 from the oxidized (hAR•NADP+•WY 14,643) and reduced (hAR•NADPH•WY 14,643) ternary complexes are comparable to each other. The ternary complex structure of hAR•NADP+•WY 14,643 reveals the first structural evidence of a fibrate class drug binding to hAR. These observations demonstrate how fibrate molecules such as WY 14,643, besides being valued as agonists for PPAR, also inhibit hAR

Inhibiting wild-type and C299S mutant AKR1B10; a homologue of aldose reductase upregulated in cancers.

AKR1B10 is an aldose reductase (AR) homologue overexpressed in liver cancer and various forms of that enzyme in carcinomas catalyze the reduction of anticancer drugs, potential cytostatic drug, and dl-glyceraldehyde but do not catalyze the reduction of glucose. Kinetic parameters for wild-type and C299S mutant AKR1B10 indicate that substitution of serine for cysteine at position 299 reduces the affinity of this protein for dl-glyceraldehyde and enhances its catalytic activity. Fibrates suppress peroxisome proliferation and the development of liver cancer in human. Here we report the potency of fibrate-mediated inhibition of the carbonyl reduction catalyzed by wild-type and C299S mutant AKR1B10 and compare it with known AR inhibitors. Wild-type AKR1B10-catalyzed carbonyl reduction follows pure non-competitive inhibition kinetics using zopolrestat, EBPC or sorbinil, whereas fenofibrate, Wy 14,643, ciprofibrate and fenofibric acid follow mixed non-competitive inhibition kinetics. In contrast, catalysis of reaction by the C299S AKR1B10 mutant is not inhibited by sorbinil and EBPC. Despite these differences, the C299S AKR1B10 mutant still manifests kinetics similar to the wild-type protein with other fibrates including zopolrestat, fenofibrate, Wy 14,346, gemfibrozil and ciprofibrate that show mixed non-competitive inhibition kinetics. The reaction of the mutant AKR1B10 is inhibited by fenofibric acid, but manifests pure non-competitive inhibition kinetics that are different from those demonstrated for the wild-type enzyme

High-resolution crystal structure of AKR11C1 from Bacillus halodurans: an NADPH-dependent 4-hydroxy-2,3-trans-nonenal reductase.

International audienceAldo-keto reductase AKR11C1 from Bacillus halodurans, a new member of aldo-keto reductase (AKR) family 11, has been characterized structurally and biochemically. The structures of the apo and NADPH bound form of AKR11C1 have been solved to 1.25 A and 1.3 A resolution, respectively. AKR11C1 possesses a novel non-aromatic stacking interaction of an arginine residue with the cofactor, which may favor release of the oxidized cofactor. Our biochemical studies have revealed an NADPH-dependent activity of AKR11C1 with 4-hydroxy-2,3-trans-nonenal (HNE). HNE is a cytotoxic lipid peroxidation product, and detoxification in alkaliphilic bacteria, such as B.halodurans, plays a crucial role in survival. AKR11C1 could thus be part of the detoxification system, which ensures the well being of the microorganism. The very poor activity of AKR11C1 on standard, small substrates such as benzaldehyde or DL-glyeraldehyde is consistent with the observed, very open active site lacking a binding pocket for these substrates. In contrast, modeling of HNE with its aldehyde function suitably positioned in the active site suggests that its elongated hydrophobic tail occupies a groove defined by hydrophobic side-chains. Multiple sequence alignment of AKR11C1 with the highly homologous iolS and YqkF proteins shows a high level of conservation in this putative substrate-binding site. We suggest that AKR11C1 is the first structurally characterized member of a new class of AKRs with specificity for substrates with long aliphatic tails

The Role of Cys-298 in Aldose Reductase Function*

Diabetic tissues are enriched in an “activated” form of human aldose reductase (hAR), a NADPH-dependent oxidoreductase involved in sugar metabolism. Activated hAR has reduced sensitivity to potential anti-diabetes drugs. The C298S mutant of hAR reproduces many characteristics of activated hAR, although it differs from wild-type hAR only by the replacement of a single sulfur atom with oxygen. Isothermal titration calorimetry measurements revealed that the binding constant of NADPH to the C298S mutant is decreased by a factor of two, whereas that of NADP+ remains the same. Similarly, the heat capacity change for the binding of NADPH to the C298S mutant is twice increased; however, there is almost no difference in the heat capacity change for binding of the NADP+ to the C298S. X-ray crystal structures of wild-type and C298S hAR reveal that the side chain of residue 298 forms a gate to the nicotinamide pocket and is more flexible for cysteine compared with serine. Unlike Cys-298, Ser-298 forms a hydrogen bond with Tyr-209 across the nicotinamide ring, which inhibits movements of the nicotinamide. We hypothesize that the increased polarity of the oxidized nicotinamide weakens the hydrogen bond potentially formed by Ser-298, thus, accounting for the relatively smaller effect of the mutation on NADP+ binding. The effects of the mutant on catalytic rate constants and binding constants for various substrates are the same as for activated hAR. It is, thus, further substantiated that activated hAR arises from oxidative modification of Cys-298, a residue near the nicotinamide binding pocket