Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.1.1.1 (alcohol dehydrogenase)
9,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Aldehyde reductase is an enzyme capable of metabolizing a wide variety of aldehydes to their corresponding alcohols. The tertiary structures of aldehyde reductase and aldose reductase are similar and consist of an alpha/beta-barrel with the active site located at the carboxy terminus of the strands of the barrel. We have determined the X-ray crystal structure of porcine aldehyde reductase holoenzyme in complex with an aldose reductase inhibitor, tolrestat, at 2.4 A resolution to obtain a picture of the binding conformation of inhibitors to aldehyde reductase. Tolrestat binds in the active site pocket of aldehyde reductase and interacts through van der Waals contacts with Arg 312 and Asp 313. The carboxylate group of tolrestat is within hydrogen bonding distance with His 113 and Trp 114. Mutation of Arg 312 to alanine in porcine aldehyde reductase alters the potency of inhibition of the enzyme by aldose reductase inhibitors. Our results indicate that the structure of the inhibitor-binding site of aldehyde reductase differs from that of aldose reductase due to the participation of nonconserved residues in its formation. A major difference is the participation of Arg 312 and Asp 313 in lining the inhibitor-binding site in aldehyde reductase but not in aldose reductase.
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PMID:Studies on the inhibitor-binding site of porcine aldehyde reductase: crystal structure of the holoenzyme-inhibitor ternary complex. 932 83

We present evidence that the size of an active site side chain may modulate the degree of hydrogen tunneling in an enzyme-catalyzed reaction. Primary and secondary kH/kT and kD/kT kinetic isotope effects have been measured for the oxidation of benzyl alcohol catalyzed by horse liver alcohol dehydrogenase at 25 degrees C. As reported in earlier studies, the relationship between secondary kH/kT and kD/kT isotope effects provides a sensitive probe for deviations from classical behavior. In the present work, catalytic efficiency and the extent of hydrogen tunneling have been correlated for the alcohol dehydrogenase-catalyzed hydride transfer among a group of site-directed mutants at position 203. Val-203 interacts with the opposite face of the cofactor NAD+ from the alcohol substrate. The reduction in size of this residue is correlated with diminished tunneling and a two orders of magnitude decrease in catalytic efficiency. Comparison of the x-ray crystal structures of a ternary complex of a high-tunneling (Phe-93 --> Trp) and a low-tunneling (Val-203 --> Ala) mutant provides a structural basis for the observed effects, demonstrating an increase in the hydrogen transfer distance for the low-tunneling mutant. The Val-203 --> Ala ternary complex crystal structure also shows a hyperclosed interdomain geometry relative to the wild-type and the Phe-93 --> Trp mutant ternary complex structures. This demonstrates a flexibility in interdomain movement that could potentially narrow the distance between the donor and acceptor carbons in the native enzyme and may enhance the role of tunneling in the hydride transfer reaction.
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PMID:A link between protein structure and enzyme catalyzed hydrogen tunneling. 937 55

Sulfoxides inhibit horse liver alcohol dehydrogenase (EqADH) by binding to the enzyme-NADH complex. X-ray crystallography suggests that sulfoxides make a cation-pi interaction with the benzene ring of Phe-93 [Cho et al. (1997) Biochemistry 36, 382-389]. Structure-function relationships were examined with seven different sulfoxides binding to five human enzymes (alpha, beta1, gamma2, pi, and sigma) and three mutated forms of the horse enzyme. The human gamma2 enzyme, EqADH, and EqADH with Phe-93 replaced with Trp were selectively and strongly inhibited (Ki </= 1 microM) by the 3-butyl or hexyl derivatives of thiolane 1-oxide. The other human enzymes (all with Thr-48) and EqADH with Ser-48 substituted with Thr had relatively lower affinities for the thiolane 1-oxides due to close contact of the methyl group of Thr-48 with a carbon adjacent to the sulfoxide sulfur. EqADH binds the S isomers of 3-butylthiolane 1-oxides, hexyl methyl sulfoxide, and phenyl methyl sulfoxide more tightly than the R isomers, but EqADH with Phe-93 substituted with Ala and the human alpha enzyme (with Ala-93) prefer (R)-phenyl methyl sulfoxide, apparently because the phenyl ring fits into the space near residue 93. EqADH and the enzymes with Phe-93 replaced with Ala or Trp had similar affinities for sulfoxides, indicating that the contribution of the cation-pi interaction to binding is small or compensated for by altered interactions. Ab initio calculations also suggest that the interaction of a sulfoxide with benzene is relatively weak.
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PMID:Specificity of alcohol dehydrogenases for sulfoxides. 952 68

Total alcohol dehydrogenase activity in the sera of 77 patients in the course of viral hepatitis was determined by means of photometric method based on p-nitrosodimethylaniline reduction. Blood samples were taken 5 times at intervals of 7 to 9 day. We found that serum total ADH activity was higher at the onset of disease than that of the control group. The highest increase of activity was observed in the first week of hospitalisation, and exceeded the mean control value about 7 times. After that, the activity of ADH gradually decreased, and reached the value of the control group in the last period of the study. During five weeks of the study the total activity of ADH showed a good linear correlation with alanine and aspartate aminotransferases. We concluded that total alcohol dehydrogenase activity measured by photometric method increase in the course of viral hepatitis and correlate with the progress and treatment of disease measured by commonly accepted enzymatic markers of liver cell damage.
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PMID:Alcohol dehydrogenase (ADH) activity in the sera of patients during the course of viral hepatitis. 958 70

The oxidation of alcohol to aldehyde by horse liver alcohol dehydrogenase (LADH) requires the transfer of a hydride ion from the alcohol substrate to the cofactor nicotinamide adenine dinucleotide (NAD). A quantum mechanical tunneling contribution to this hydride transfer step has been demonstrated in a number of LADH mutants designed to enhance or diminish this effect [Bahnson, B. J., et al. (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 12797-12802]. The active site double mutant Phe93 --> Trp/Val203 --> Ala shows a 75-fold reduction in catalytic efficiency relative to that of the native enzyme, and reduced tunneling relative to that of either single mutant. We present here two crystal structures of the double mutant: a 2.0 A complex with NAD and the substrate analogue trifluoroethanol and a 2.6 A complex with the isosteric NAD analogue CPAD and ethanol. Changes at the active site observed in both complexes are consistent with reduced activity and tunneling. The NAD-trifluoroethanol complex crystallizes in the closed conformation characteristic of the active enzyme. However, the NAD nicotinamide ring rotates away from the substrate, toward the space vacated by replacement of Val203 with the smaller alanine. Replacement of Phe93 with the larger tryptophan also produces unfavorable steric contacts with the nicotinamide carboxamide group, potentially destabilizing hydrogen bonds required to maintain the closed conformation. These contacts are relieved in the second complex by rotation of the CPAD pyridine ring into an unusual syn orientation. The resulting loss of the carboxamide hydrogen bonds produces an open conformation characteristic of the apoenzyme.
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PMID:Active site modifications in a double mutant of liver alcohol dehydrogenase: structural studies of two enzyme-ligand complexes. 964 10

A comparison of the three-dimensional structures of the closely related mesophilic Clostridium beijerinckii alcohol dehydrogenase (CBADH) and the hyperthermophilic Thermoanaerobacter brockii alcohol dehydrogenase (TBADH) suggested that extra proline residues in TBADH located in strategically important positions might contribute to the extreme thermal stability of TBADH. We used site-directed mutagenesis to replace eight complementary residue positions in CBADH, one residue at a time, with proline. All eight single-proline mutants and a double-proline mutant of CBADH were enzymatically active. The critical sites for increasing thermostability parameters in CBADH were Leu-316 and Ser-24, and to a lesser degree, Ala-347. Substituting proline for His-222, Leu-275, and Thr-149, however, reduced thermal stability parameters. Our results show that the thermal stability of the mesophilic CBADH can be moderately enhanced by substituting proline at strategic positions analogous to nonconserved prolines in the homologous thermophilic TBADH. The proline residues that appear to be crucial for the increased thermal stability of CBADH are located at a beta-turn and a terminating external loop in the polypeptide chain. Positioning proline at the N-caps of alpha-helices in CBADH led to adverse effects on thermostability, whereas single-proline mutations in other positions in the polypeptide had varying effects on thermal parameters. The finding presented here support the idea that at least two of the eight extra prolines in TBADH contribute to its thermal stability.
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PMID:Enhanced thermal stability of Clostridium beijerinckii alcohol dehydrogenase after strategic substitution of amino acid residues with prolines from the homologous thermophilic Thermoanaerobacter brockii alcohol dehydrogenase. 983 74

The objective of this study was to determine the effects of a country liquor Toddy (Coconut palm wine) and an equivalent quantity of ethanol on liver function and lipid metabolism in utero. Female albino rats with an average weight of 125 +/- 5 g were exposed to Toddy from coconut palm (24.5 ml/kg body weight/day) and ethanol (0.52 ml/kg body weight/day) for 15 days before conception and during pregnancy. On day 13 and day 19 of gestation, altered liver function and hyperlipidemia were seen in the fetuses of both the treated groups. Altered liver function was evidenced by the increased activity of alcohol dehydrogenase, aldehyde dehydrogenase, glutamic oxaloacetic transaminase (aspartate amino transferase (GOT)), glutamic pyruvic transaminase (alanine amino transferase (GPT)). Hyperlipidemia was caused by increased biosynthesis since the incorporation of 14C acetate into lipids and activities of HMG CoA reductase and lipogenic enzymes were elevated. Toddy treated fetuses were more severely affected than those exposed to an equivalent quantity of ethanol. Toddy seemed to potentiate the toxicity induced by alcohol suggesting the role of non alcoholic components. Hepatic functions of the day 13 fetuses were effected to a lesser degree than those in the day 19 hepatic liver.
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PMID:Effect of in utero exposure of Toddy (coconut palm wine) on liver function and lipid metabolism in rat fetuses. 995 82

Yeast (Saccharomyces cerevisiae) alcohol dehydrogenase I (SceADH) binds NAD+ and NADH less tightly and turns over substrates more rapidly than does horse (Equus caballus) liver alcohol dehydrogenase E isoenzyme (EcaADH), and neither enzyme uses NADP efficiently. Amino acid residues in the proposed adenylate binding pocket of SceADH were substituted in attempts to improve affinity for coenzymes or reactivity with NADP. Substitutions in SceADH (Gly202Ile or Ser246Ile) with the corresponding residues in the adenine binding site of the homologous EcaADH have modest effects on coenzyme binding and other kinetic constants, but the Ser246Ile substitution decreases turnover numbers by 350-fold. The Ser176Phe substitution (also near adenine site) significantly decreases affinity for coenzymes and turnover numbers. In the consensus nucleotide-binding betaalphabeta fold sequence, SceADH has two alanine residues (177-GAAGGLG-183) instead of the Leu200 in EcaADH (199-GLGGVG-204); the Ala178-Ala179 to Leu substitution significantly decreases affinity for coenzymes and turnover numbers. Some NADP-dependent enzymes have an Ala corresponding to Gly183 in SceADH; the Gly183Ala substitution significantly decreases affinity for coenzymes and turnover numbers. NADP-dependent enzymes usually have a neutral residue instead of the Asp (Asp201 in SceADH) that interacts with the hydroxyl groups of the adenosine ribose, along with a basic residue (at position 202 or 203) to stabilize the 2'-phosphate of NADP. The Gly203Arg change in SceADH does not significantly affect the kinetics. The Gly183Ala or Gly203Arg substitutions do not enable SceADH to use NADP+ as coenzyme. SceADH with the single Asp201Gly or double Asp201Gly:Gly203Arg substitutions have similar, low activity with NADP+. The results suggest that several of the amino acid residues participate in coenzyme binding and that conversion of specificity for coenzyme requires multiple substitutions.
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PMID:Probing the affinity and specificity of yeast alcohol dehydrogenase I for coenzymes. 1039 40

A tunneling contribution to hydride transfer has been demonstrated previously in the oxidation of benzyl alcohol catalyzed by an active-site mutant (F93W) of horse liver alcohol dehydrogenase (LADH) [Bahnson, B. J., et al. (1993) Biochemistry 32, 5503-5507]. Mutation of a residue that lies directly behind the nicotinamide ring of the bound cofactor has further shown that side-chain bulk can contribute to catalytic efficiency and tunneling in a correlated fashion [Bahnson, B. J., et al. (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 12797-12802]. Second site mutations of F93W have now been made at positions more remote from the active site. In particular, we have focused on an isoleucine residue that interacts with the adenine moiety of the NAD(+) cofactor, 20 A from the nicotinamide ring. Replacement of this remote residue with glycine (F93W:I224G), alanine (F93W:I224A), valine (F93W:I224V), and leucine (F93W:I224L) is concluded to destabilize the binding of NAD(+). All double mutants exhibited a K(M) for NAD(+) that is 2-25 times higher than that for the F93W enzyme. However, neither the catalytic efficiency for turnover of benzyl alcohol [k(cat)/K(M(benzyl alcohol))] nor the relationship between the secondary k(H)/k(T) and k(D)/k(T) isotope effects for benzyl alcohol oxidation was significantly affected. The lack of differences observed in the isotope effects indicates that these mutations have little effect on the extent of hydrogen tunneling in the reaction. The complete removal of the side chain at position 224 in the F93W:I224G enzyme resulted in a less than 5% decrease in the ratio of the secondary isotope effects, maintaining the ratio above the semiclassical limit for the indication of tunneling in the reaction. By contrast, K(i) for NAD(+) increased 60-fold for this mutant. The results obtained with F93W:I224G are consistent with remote interactions that affect the association and binding of cofactor in a reactive conformation. However, once this conformation is achieved, hydride transfer and its tunneling component proceed as with the single F93W mutant enzyme, uninfluenced by the remote mutation. Replacement of other side chains, with alpha-carbon positions from about 8 to over 20 A from the C4 position of the nicotinamide ring, demonstrated a similar insensitivity of k(cat)/K(M(benzyl alcohol)) to protein modification. Comparison to earlier studies with active-site mutants of LADH implicates a role for proximal, but not distal, side chains in the modulation of hydrogen tunneling for this enzyme.
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PMID:Probes of a role for remote binding interactions on hydrogen tunneling in the horse liver alcohol dehydrogenase reaction. 1068 7

The objective of this study was to determine the effects of a country liquor (Arrack) and the equivalent quantity of ethanol on liver function and lipid metabolism in utero. Female rats of average weight 125 g were exposed to Arrack (12 ml/kg body weight/day) and ethanol (3.2 ml/kg body weight/day) for 15 days before conception and throughout gestation. On 13th day and 19th day of gestation, altered liver function and hyperlipidemia was seen in the fetus of both the treated groups. Altered liver function was evidenced by the increased activity of alcohol dehydrogenase and glutamic pyruvic transaminase or alanine amino transferase (GPT). Hyperlipidemia was caused by increased biosynthesis since the incorporation of 14C acetate to lipids and activities of HMG CoA reductase and lipogenic enzymes were elevated. Arrack seemed to potentiate the toxicity induced by alcohol indicating the role of non ethanolic portion. Hepatic functions of the 13th day fetuses were effected to a lesser degree than the 19th day hepatic liver.
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PMID:Prenatal exposure of an alcoholic beverage (Arrack) on fetal lipid metabolism in rats. 1094 14


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