Catalyzes the NADPH-dependent reduction of a variety of aromatic and aliphatic aldehydes to their corresponding alcohols. Catalyzes the reduction of mevaldate to mevalonic acid and of glyceraldehyde to glycerol. Has broad substrate specificity. In vitro substrates include succinic semialdehyde, 4-nitrobenzaldehyde, 1,2-naphthoquinone, methylglyoxal, and D-glucuronic acid. Plays a role in the activation of procarcinogens, such as polycyclic aromatic hydrocarbon trans-dihydrodiols, and in the metabolism of various xenobiotics and drugs, including the anthracyclines doxorubicin (DOX) and daunorubicin (DAUN).
Aldo-keto reductases (AKRs) are a class of NADPH-dependent oxidoreductases that have been linked to metabolism of the anthracyclines doxorubicin (DOX) and daunorubicin (DAUN). Although widely used, cardiotoxicity continues to be a serious side effect that may be linked to metabolites or reactive intermediates generated in their metabolism. In this study we examine the little known effects of nonsynonymous single nucleotide polymorphisms of human AKR1A1 on the metabolism of these drugs to their alcohol metabolites. Expressed and purified from bacteria using affinity chromatography, the AKR1A1 protein with a single histidine (6x-His) tag exhibited the greatest activity using two test substrates: p-nitrobenzaldehyde (5.09 +/- 0.16 micromol/min/mg of purified protein) and DL-glyceraldehyde (1.24 +/- 0.17 micromol/min/mg). These activities are in agreement with published literature values of nontagged human AKR1A1. The 6x-His-tagged AKR1A1 wild type and allelic variants, E55D and N52S, were subsequently examined for metabolic activity using DAUN and DOX. The tagged variants showed significantly reduced activities (1.10 +/- 0.42 and 0.72 +/- 0.47 nmol of daunorubicinol (DAUNol) formed/min/mg of purified protein for E55D and N52S, respectively) compared with the wild type (2.34 +/- 0.71 nmol/min/mg). The wild type and E55D variant metabolized DOX to doxorubicinol (DOXol); however, the levels fell below the limit of quantitation (25 nM). The N52S variant yielded no detectable DOXol. A kinetic analysis of the DAUN reductase activities revealed that both amino acid substitutions lead to reduced substrate affinity, measured as significant increases in the measured K(m) for the reduction reaction by AKR1A1. Hence, it is possible that these allelic variants can act as genetic biomarkers for the clinical development of DAUN-induced cardiotoxicity.
Polycyclic aromatic hydrocarbons (PAHs) are metabolized to trans-dihydrodiol proximate carcinogens by CYP1A1 and epoxide hydrolase (EH). CYP1A1 or aldo-keto reductases (AKRs) from the 1C subfamily can further activate the trans-dihydrodiols by forming either anti-diol-epoxides or reactive and redox active o-quinones, respectively. To determine whether other AKR superfamily members can divert trans-dihydrodiols to o-quinones, the cDNA encoding human aldehyde reductase (AKR1A1) was isolated from hepatoma HepG2 cells using RT-PCR, subcloned into a prokaryotic expression vector, overexpressed in E. coli and purified to homogeneity in milligram amounts. Studies revealed that AKR1A1 preferentially oxidized the metabolically relevant (-)-[3R,4R]-dihydroxy-3,4-dihydrobenz[a]anthracene. AKR1A1 also displayed high utilization ratios (V(max)/K(m)) for the following PAH trans-dihydrodiols: (+/-)trans-3,4-dihydroxy-3,4-dihydro-7-methylbenz[a]anthracene, (+/-)trans-3,4-dihydroxy-3,4-dihydro-7,12-dimethylbenz[a]anthracene and (+/-)trans-7,8-dihydroxy-7,8-dihydro-5-methylchrysene. Multiple tissue expression (MTE) arrays were used to measure the co-expressed of CYP1A1, EH and AKR1A1. All the three enzymes co-expressed to sites of PAH activation. The high catalytic efficiency of AKR1A1 for potent proximate carcinogen trans-dihydrodiols and its presence in tissues that contain CYP1A1 and EH suggests that it plays an important role in this alternative pathway of PAH activation (supported by CA39504).
Biochem. J. 343 Pt 2, 487-504 (1999)[PubMed:10510318]
Complementary DNA clones encoding human aflatoxin B(1) aldehyde reductase (AKR7A2), aldehyde reductase (AKR1A1), aldose reductase (AKR1B1), dihydrodiol dehydrogenase 1 (AKR1C1) and chlordecone reductase (AKR1C4) have been expressed in Escherichia coli. These members of the aldo-keto reductase (AKR) superfamily have been purified from E. coli as recombinant proteins. The recently identified AKR7A2 was shown to differ from the AKR1 isoenzymes in being able to catalyse the reduction of 2-carboxybenzaldehyde. Also, AKR7A2 was found to exhibit a narrow substrate specificity, with activity being restricted to succinic semialdehyde (SSA), 2-nitrobenzaldehyde, pyridine-2-aldehyde, isatin, 1,2-naphthoquinone (1,2-NQ) and 9,10-phenanthrenequinone. In contrast, AKR1A1 reduces a broad spectrum of carbonyl-containing compounds, displaying highest specific activity for SSA, 4-carboxybenzaldehyde, 4-nitrobenzaldehyde, pyridine-3-aldehyde, pyridine-4-aldehyde, 4-hydroxynonenal, phenylglyoxal, methylglyoxal, 2,3-hexanedione, 1, 2-NQ, 16-ketoestrone and d-glucuronic acid. Comparison between the kinetic properties of AKR7A2 and AKR1A1 showed that both recombinant enzymes exhibited roughly similar k(cat)/K(m) values for SSA, 1,2-NQ and 16-ketoestrone. Many of the compounds which are substrates for AKR1A1 also serve as substrates for AKR1B1, though the latter enzyme was shown to display a specific activity significantly less than that of AKR1A1 for most of the aromatic and aliphatic aldehydes studied. Neither AKR1C1 nor AKR1C4 was found to possess high reductase activity towards aliphatic aldehydes, aromatic aldehydes, aldoses or dicarbonyls. However, unlike AKR1A1 and AKR1B1, both AKR1C1 and AKR1C4 were able to catalyse the oxidation of 1-acenaphthenol and, in addition, AKR1C4 could oxidize di- and tri-hydroxylated bile acids. Specific antibodies raised against AKR7A2, AKR1A1, AKR1B1, AKR1C1 and AKR1C4 have been used to show the presence of all of the reductases in human hepatic cytosol; the levels of AKR1B1 and AKR1C1 were markedly elevated in livers with alcohol-associated injury, and indeed AKR1B1 was only detectable in livers with evidence of alcoholic liver disease. Western blotting of extracts from brain, heart, kidney, liver, lung, prostate, skeletal muscle, small intestine, spleen and testis showed that AKR7A2 is present in all of the organs examined, and AKR1B1 is similarly widely distributed in human tissues. These experiments revealed however, that the expression of AKR1A1 is restricted primarily to brain, kidney, liver and small intestine. The AKR1C family members proved not to be as widely expressed as the other reductases, with AKR1C1 being observed in only kidney, liver and testis, and AKR1C4 being found in liver alone. As human kidney is a rich source of AKR, the isoenzymes in this organ have been studied further. Anion-exchange chromatography of human renal cytosol on Q-Sepharose allowed resolution of AKR1A1, AKR1B1, AKR1C1 and AKR7A2, as identified by substrate specificity and Western blotting. Immunohistochemistry of human kidney demonstrated that AKR7A2 is expressed in a similar fashion to the AKR1 family members in proximal and distal convoluted renal tubules. Furthermore, both AKR7A2 and AKR1 members were expressed in renal carcinoma cells, suggesting that these groups of isoenzymes may be engaged in related physiological functions.
J. Biol. Chem. 264, 9547-9551 (1989)[PubMed:2498333]
Aldehyde reductase [EC 1.1.1.2] and aldose reductase [EC 1.1.1.21] are monomeric NADPH-dependent oxidoreductases having wide substrate specificities for carbonyl compounds. These enzymes are implicated in the development of diabetic complications by catalyzing the reduction of glucose to sorbitol. Enzyme inhibition as a direct pharmacokinetic approach to the prevention of diabetic complications resulting from the hyperglycemia of diabetes has not been effective because of nonspecificity of the inhibitors and some appreciable side effects. To understand the structural and evolutionary relationship of these enzymes, we cloned and sequenced cDNAs coding for aldose and aldehyde reductases from human liver and placental cDNA libraries. Human placental aldose reductase (open reading frame of 316 amino acids) has a 65% identity (identical plus conservative substitutions) to human liver and placental aldehyde reductase (open reading frame of 325 amino acids). The two sequences have significant identity to 2,5-diketogluconic acid reductase from corynebacterium, frog rho-crystallin, and bovine lung prostaglandin F synthase (reductase). Southern hybridization analysis of human genomic DNA indicates a multigene system for aldose reductase, suggesting the existence of additional proteins. Thus, the aldo-keto reductase superfamily of proteins may have a more significant and hitherto not fully appreciated role in general cellular metabolism.
J. Biol. Chem. 264, 9547-9551 (1989)[PubMed:2498333]
Aldehyde reductase [EC 1.1.1.2] and aldose reductase [EC 1.1.1.21] are monomeric NADPH-dependent oxidoreductases having wide substrate specificities for carbonyl compounds. These enzymes are implicated in the development of diabetic complications by catalyzing the reduction of glucose to sorbitol. Enzyme inhibition as a direct pharmacokinetic approach to the prevention of diabetic complications resulting from the hyperglycemia of diabetes has not been effective because of nonspecificity of the inhibitors and some appreciable side effects. To understand the structural and evolutionary relationship of these enzymes, we cloned and sequenced cDNAs coding for aldose and aldehyde reductases from human liver and placental cDNA libraries. Human placental aldose reductase (open reading frame of 316 amino acids) has a 65% identity (identical plus conservative substitutions) to human liver and placental aldehyde reductase (open reading frame of 325 amino acids). The two sequences have significant identity to 2,5-diketogluconic acid reductase from corynebacterium, frog rho-crystallin, and bovine lung prostaglandin F synthase (reductase). Southern hybridization analysis of human genomic DNA indicates a multigene system for aldose reductase, suggesting the existence of additional proteins. Thus, the aldo-keto reductase superfamily of proteins may have a more significant and hitherto not fully appreciated role in general cellular metabolism.
J. Biol. Chem. 264, 9547-9551 (1989)[PubMed:2498333]
Aldehyde reductase [EC 1.1.1.2] and aldose reductase [EC 1.1.1.21] are monomeric NADPH-dependent oxidoreductases having wide substrate specificities for carbonyl compounds. These enzymes are implicated in the development of diabetic complications by catalyzing the reduction of glucose to sorbitol. Enzyme inhibition as a direct pharmacokinetic approach to the prevention of diabetic complications resulting from the hyperglycemia of diabetes has not been effective because of nonspecificity of the inhibitors and some appreciable side effects. To understand the structural and evolutionary relationship of these enzymes, we cloned and sequenced cDNAs coding for aldose and aldehyde reductases from human liver and placental cDNA libraries. Human placental aldose reductase (open reading frame of 316 amino acids) has a 65% identity (identical plus conservative substitutions) to human liver and placental aldehyde reductase (open reading frame of 325 amino acids). The two sequences have significant identity to 2,5-diketogluconic acid reductase from corynebacterium, frog rho-crystallin, and bovine lung prostaglandin F synthase (reductase). Southern hybridization analysis of human genomic DNA indicates a multigene system for aldose reductase, suggesting the existence of additional proteins. Thus, the aldo-keto reductase superfamily of proteins may have a more significant and hitherto not fully appreciated role in general cellular metabolism.
The chemical reactions and pathways involving glucose, the aldohexose gluco-hexose. D-glucose is dextrorotatory and is sometimes known as dextrose; it is an important source of energy for living organisms and is found free as well as combined in homo- and hetero-oligosaccharides and polysaccharides.
J. Biol. Chem. 264, 9547-9551 (1989)[PubMed:2498333]
Aldehyde reductase [EC 1.1.1.2] and aldose reductase [EC 1.1.1.21] are monomeric NADPH-dependent oxidoreductases having wide substrate specificities for carbonyl compounds. These enzymes are implicated in the development of diabetic complications by catalyzing the reduction of glucose to sorbitol. Enzyme inhibition as a direct pharmacokinetic approach to the prevention of diabetic complications resulting from the hyperglycemia of diabetes has not been effective because of nonspecificity of the inhibitors and some appreciable side effects. To understand the structural and evolutionary relationship of these enzymes, we cloned and sequenced cDNAs coding for aldose and aldehyde reductases from human liver and placental cDNA libraries. Human placental aldose reductase (open reading frame of 316 amino acids) has a 65% identity (identical plus conservative substitutions) to human liver and placental aldehyde reductase (open reading frame of 325 amino acids). The two sequences have significant identity to 2,5-diketogluconic acid reductase from corynebacterium, frog rho-crystallin, and bovine lung prostaglandin F synthase (reductase). Southern hybridization analysis of human genomic DNA indicates a multigene system for aldose reductase, suggesting the existence of additional proteins. Thus, the aldo-keto reductase superfamily of proteins may have a more significant and hitherto not fully appreciated role in general cellular metabolism.
The chemical reactions and pathways resulting in the formation of L-ascorbic acid; L-ascorbic acid ionizes to give L-ascorbate, (2R)-2-[(1S)-1,2-dihydroxyethyl]-4-hydroxy-5-oxo-2,5-dihydrofuran-3-olate, which is required as a cofactor in the oxidation of prolyl residues to hydroxyprolyl, and other reactions.
IEAOrtholog Compara
Enzymatic activity
This protein acts as an enzyme. It is known to catalyze the following reaction
EC 1.1.1.2: An alcohol + NADP(+) ⇄ an aldehyde + NADPH.
CuratedUniProtKB
Pathways
According to KEGG, this protein belongs to the following pathways:
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
My favorites 
My labels 
Login
