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'''Alcohol dehydrogenases''' ('''ADH''') ({{EC number|1.1.1.1}}) are a group of seven [[dehydrogenase]] [[enzyme]]s that occur in many organisms and facilitate the interconversion between [[alcohol]]s and [[aldehyde]]s or [[ketone]]s with the reduction of NAD<sup>+</sup> to NADH. In [[human]]s and many other [[animal]]s, they serve to break down alcohols which could otherwise be toxic; in [[yeast]], plants and many [[bacterium|bacteria]], some alcohol dehydrogenases [[catalysis|catalyze]] the opposite reaction as part of [[fermentation (food)|fermentation]] to ensure a constant supply of NAD<sup>+</sup>.
'''Alcohol dehydrogenases''' ('''ADH''') ({{EC number|1.1.1.1}}) are a group of [[dehydrogenase]] [[enzyme]]s that occur in many organisms and facilitate the interconversion between [[alcohol]]s and [[aldehyde]]s or [[ketone]]s with the reduction of NAD<sup>+</sup> to NADH. In [[human]]s and many other [[animal]]s, they serve to break down alcohols which could otherwise be toxic, and they also participate in generation of useful aldehyde, ketone, or alcohol groups during biosynthesis of various metabolites. In [[yeast]], plants and many [[bacterium|bacteria]], some alcohol dehydrogenases [[catalysis|catalyze]] the opposite reaction as part of [[fermentation (food)|fermentation]] to ensure a constant supply of NAD<sup>+</sup>.


== Evolution ==
== Evolution ==
Line 55: Line 55:
== Types ==
== Types ==
=== Human ===
=== Human ===
In humans, ADH exists in multiple forms as a dimer and is encoded by at least seven different genes. There are five classes (I-V) of alcohol dehydrogenase, but the [[hepatic]] form that is primarily used in humans is class 1. Class 1 consists of A,B, and C subunits that are encoded by the genes [[ADH1A]], [[ADH1B]], and [[ADH1C]].<ref name="pmid14718645">{{cite journal | author = Sultatos LG, Pastino GM, Rosenfeld CA, Flynn EJ | title = Incorporation of the genetic control of alcohol dehydrogenase into a physiologically based pharmacokinetic model for ethanol in humans | journal = Toxicological Sciences : an Official Journal of the Society of Toxicology | volume = 78 | issue = 1 | pages = 20–31 | year = 2004 | month = March | pmid = 14718645 | doi = 10.1093/toxsci/kfh057 | url = | issn = }}</ref> The enzyme is contained in the lining of the [[stomach]] and in the [[liver]]. It catalyzes the [[oxidation]] of [[ethanol]] to [[acetaldehyde]]:
In humans, ADH exists in multiple forms as a dimer and is encoded by at least seven different genes. There are five classes (I-V) of alcohol dehydrogenase, but the [[hepatic]] form that is primarily used in humans is class 1. Class 1 consists of A,B, and C subunits that are encoded by the genes [[ADH1A]], [[ADH1B]], and [[ADH1C]].<ref name="pmid14718645">{{cite journal | author = Sultatos LG, Pastino GM, Rosenfeld CA, Flynn EJ | title = Incorporation of the genetic control of alcohol dehydrogenase into a physiologically based pharmacokinetic model for ethanol in humans | journal = Toxicological Sciences : an Official Journal of the Society of Toxicology | volume = 78 | issue = 1 | pages = 20–31 | year = 2004 | month = March | pmid = 14718645 | doi = 10.1093/toxsci/kfh057 | url = | issn = }}</ref> The enzyme is present at high levels in the [[liver]] and the lining of the [[stomach]]. It catalyzes the [[oxidation]] of [[ethanol]] to [[acetaldehyde]]:
:CH<sub>3</sub>CH<sub>2</sub>OH + NAD<sup>+</sup> → CH<sub>3</sub>CHO + [[NADH]] + H<sup>+</sup>
:CH<sub>3</sub>CH<sub>2</sub>OH + NAD<sup>+</sup> → CH<sub>3</sub>CHO + [[NADH]] + H<sup>+</sup>
This allows the consumption of [[alcoholic beverage]]s, but its evolutionary purpose is probably the breakdown of alcohols naturally contained in foods or produced by [[bacterium|bacteria]] in the [[digestive tract]]. Others believe that its evolutionary purpose is involved in vitamin A metabolism, as alcohols are relatively 'empty' calories, providing little net nutritional benefit.{{Citation needed|date=December 2008}}
This allows the consumption of [[alcoholic beverage]]s, but its evolutionary purpose is probably the breakdown of alcohols naturally contained in foods or produced by [[bacterium|bacteria]] in the [[digestive tract]] as alcohols are relatively 'empty' calories, providing little net nutritional benefit.<ref>http://www.medicinenet.com/alcohol_and_nutrition/article.htm</ref> Another evolutionary purpose may be metabolism of the endogenous alcohol [[vitamin A]] ([[retinol]]) which generates the hormone [[retinoic acid]].<ref name="Duester">Duester, G. (2008) Retinoic acid synthesis and signaling during early organogenesis. Cell 134: 921-931. PMCID: [http://www.pubmedcentral.gov/articlerender.fcgi?tool=nihms&artid=2632951 PMC2632951]</ref>


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Revision as of 00:10, 16 September 2010

alcohol dehydrogenase
Crystallographic structure of the
homodimer of human ADH5.[1]
Identifiers
EC no.1.1.1.1
CAS no.9031-72-5
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO
Search
PMCarticles
PubMedarticles
NCBIproteins

Alcohol dehydrogenases (ADH) (EC 1.1.1.1) are a group of dehydrogenase enzymes that occur in many organisms and facilitate the interconversion between alcohols and aldehydes or ketones with the reduction of NAD+ to NADH. In humans and many other animals, they serve to break down alcohols which could otherwise be toxic, and they also participate in generation of useful aldehyde, ketone, or alcohol groups during biosynthesis of various metabolites. In yeast, plants and many bacteria, some alcohol dehydrogenases catalyze the opposite reaction as part of fermentation to ensure a constant supply of NAD+.

Evolution

Genetic evidence from comparisons of multiple organisms, showed that a glutathione dependent formaldehyde dehydrogenase, identical to an ADH3, probably is the ancestral enzyme for the entire ADH family.[2][3] Early on in evolution, an effective method for eliminating endogenous and exogenous formaldehyde was important and this capacity has conserved the ancestral ADH3 through time. From genetic duplications of ADH3, followed by series of mutations, the other ADHs evolved.[2][3] The ability to produce ethanol from sugar is believed to have evolved in yeast. This feature is not rational from an energetic point of view, but by making alcohol in such high concentrations so that they were toxic to other organisms, yeast cells could effectively eliminate their competition. Since rotting fruit can contain more than 4% of ethanol, animals eating the fruit needed a system to metabolize exogenous ethanol. This can explain the need for an ethanol active ADH in other species than yeast.

Discovery

The first ever isolated alcohol dehydrogenase (ADH) was purified in 1937 from Saccharomyces cerevisiae (baker’s yeast).[4] Many aspects of the catalytic mechanism for the horse liver ADH enzyme was investigated by Hugo Theorell and coworkers.[5] ADH was also one of the first oligomeric enzymes that had its amino acid sequence and three dimensional structure determined.[6][7][8]

In the beginning of 1960 it was discovered in fruit flies of the genus Drosophila.[9]

Properties

The alcohol dehydrogenases comprise a group of several isozymes that facilitate the conversion of toxic alcohols to aldehydes. In mammals this is a redox (reduction/oxidation) reaction involving the coenzyme nicotinamide adenine dinucleotide (NAD+)

Alcohol dehydrogenase is a dimer with a mass of 80 kDa.[10]

Alcohol dehydrogenase is responsible for catalyzing oxidation of primary and secondary alcohols to aldehydes and ketones, respectively, and also can catalyse the reverse reaction.[9]

Oxidation of alcohol

Mechanism of action in humans

Steps

  1. Binding of the coenzyme NAD+;
  2. Binding of the alcohol substrate by coordination to zinc;
  3. Deprotonation of His-51;
  4. Deprotonation of nicotinamide ribose;
  5. Deprotonation of Ser-48;
  6. Deprotonation of the alcohol;
  7. Hydride transfer from the alkoxide ion to NAD+, leading to NADH and a zinc bound aldehyde or ketone;
  8. Release of the product aldehyde;

The mechanism in yeast and bacteria is the reverse of this reaction. These steps are supported through kinetic studies.[10]

Involved subunits

The substrate is coordinated to the zinc and this enzyme has two zinc atoms per subunit. One is the active site, which is involved in catalysis. In the active site, the ligands are Cys-46, Cys-174,His-67 and one water molecule. The other subunit is involved with structure. In this mechanism, the hydride from the alcohol goes to NAD+. Crystal structures indicate that the His-51 deprotonates the nicotinamide ribose, which deprotonates Ser-48. Finally, Ser-48 deprotonates the alcohol, making it an aldehyde.[10] From a mechanistic perspective, if the enzyme adds hydride to the re face of NAD+, the resulting hydrogen is incorporated into the pro-R position. Enzymes that add hydride to the re face are deemed Class A dehydrogenases.

Active site

The active site of alcohol dehydrogenase

The active site consists of a zinc atom, His-67, Cys-174, Cys-46, Ser-48, His-51, Ile-269, Val-292, Ala-317, and Phe-319. The zinc coordinates the substrate(alcohol). The zinc is coordinated by Cys-146, Cys-174, and His-67. Phe-319, Ala-317, His-51, Ile-269 and Val-292 stabilize NAD+ by forming hydrogen bonds. His-51 and Ile-269 form hydrogen bonds with the alcohols on nicotinamide ribose. Phe-319, Ala-317 and Val-292 form hydrogen bonds with the amide on NAD+.[10]

Structural zinc site

The structural zinc binding motif in alcohol dehydrogenase from a MD simulation

Mammalian alcohol dehydrogenases also has a structural zinc site. This Zn ion plays a structural role and is crucial for protein stability. The structures of the catalytic and structural zinc sites in horse liver alcohol dehydrogenase (HLADH) as revealed in crystallographic structures which has been studied computationally with quantum chemical as well as with classical molecular dynamics methods. The structural zinc site is composed of four closely spaced cysteine ligands (Cys97, Cys100, Cys103 and Cys111 in the amino acid sequence) positioned in an almost symmetric tetrahedron around the Zn ion. A recent study showed that the interaction between zinc and cysteine is governed by primarily an electrostatic contribution with an additional covalent contribution to the binding.[11]

Types

Human

In humans, ADH exists in multiple forms as a dimer and is encoded by at least seven different genes. There are five classes (I-V) of alcohol dehydrogenase, but the hepatic form that is primarily used in humans is class 1. Class 1 consists of A,B, and C subunits that are encoded by the genes ADH1A, ADH1B, and ADH1C.[12] The enzyme is present at high levels in the liver and the lining of the stomach. It catalyzes the oxidation of ethanol to acetaldehyde:

CH3CH2OH + NAD+ → CH3CHO + NADH + H+

This allows the consumption of alcoholic beverages, but its evolutionary purpose is probably the breakdown of alcohols naturally contained in foods or produced by bacteria in the digestive tract as alcohols are relatively 'empty' calories, providing little net nutritional benefit.[13] Another evolutionary purpose may be metabolism of the endogenous alcohol vitamin A (retinol) which generates the hormone retinoic acid.[14]

alcohol dehydrogenase 1A,
α polypeptide
Identifiers
SymbolADH1A
Alt. symbolsADH1
NCBI gene124
HGNC249
OMIM103700
RefSeqNM_000667
UniProtP07327
Other data
EC number1.1.1.1
LocusChr. 4 q23
Search for
StructuresSwiss-model
DomainsInterPro
alcohol dehydrogenase 1B,
β polypeptide
Identifiers
SymbolADH1B
Alt. symbolsADH2
NCBI gene125
HGNC250
OMIM103720
RefSeqNM_000668
UniProtP00325
Other data
EC number1.1.1.1
LocusChr. 4 q23
Search for
StructuresSwiss-model
DomainsInterPro
alcohol dehydrogenase 1C,
γ polypeptide
Identifiers
SymbolADH1C
Alt. symbolsADH3
NCBI gene126
HGNC251
OMIM103730
RefSeqNM_000669
UniProtP00326
Other data
EC number1.1.1.1
LocusChr. 4 q23
Search for
StructuresSwiss-model
DomainsInterPro

Alcohol dehydrogenase is also involved in the toxicity of other types of alcohol: for instance, it oxidizes methanol to produce formaldehyde and ethylene glycol to ultimately yield glycolic and oxalic acids. Humans have at least six slightly different alcohol dehydrogenases. Each is a dimer (i.e., consists of two polypeptides), with each dimer containing two zinc ions Zn2+. One of those ions is crucial for the operation of the enzyme: it is located at the catalytic site and holds the hydroxyl group of the alcohol in place.

Alcohol dehydrogenase activity varies between men and women, between young and old, and among populations from different areas of the world. For example, young women are unable to process alcohol at the same rate as young men because they do not express the alcohol dehydrogenase as highly. Though, the inverse is true amongst the middle-aged.[15] The level of activity may not only be dependent on level of expression but due to allelic diversity among the population.

The human genes that encode class II, III, IV, and V alcohol dehydrogenases are ADH4, ADH5, ADH7, and ADH6, respectively.

alcohol dehydrogenase 4
(class II), π polypeptide
Identifiers
SymbolADH4
NCBI gene127
HGNC252
OMIM103740
RefSeqNM_000670
UniProtP08319
Other data
EC number1.1.1.1
LocusChr. 4 q22
Search for
StructuresSwiss-model
DomainsInterPro
alcohol dehydrogenase 5
(class III), χ polypeptide
Identifiers
SymbolADH5
NCBI gene128
HGNC253
OMIM103710
RefSeqNM_000671
UniProtP11766
Other data
EC number1.1.1.1
LocusChr. 4 q23
Search for
StructuresSwiss-model
DomainsInterPro
alcohol dehydrogenase 6
(class V)
Identifiers
SymbolADH6
NCBI gene130
HGNC255
OMIM103735
RefSeqNM_000672
UniProtP28332
Other data
EC number1.1.1.1
LocusChr. 4 q23
Search for
StructuresSwiss-model
DomainsInterPro
alcohol dehydrogenase 7
(class IV), μ or σ polypeptide
Identifiers
SymbolADH7
NCBI gene131
HGNC256
OMIM600086
RefSeqNM_000673
UniProtP40394
Other data
EC number1.1.1.1
LocusChr. 4 q23-q24
Search for
StructuresSwiss-model
DomainsInterPro

Yeast and bacteria

Unlike humans, yeast and bacteria (except lactic acid bacteria, and E. coli in certain conditions ) do not ferment glucose to lactate. Instead, they ferment it to ethanol and CO2. The overall reaction can be seen below:

Glucose + 2 ADP + 2 Pi → 2 ethanol + 2 CO2 + 2 ATP + 2 H2O[16]

In yeast and many bacteria, alcohol dehydrogenase plays an important part in fermentation: pyruvate resulting from glycolysis is converted to acetaldehyde and carbon dioxide, and the acetaldehyde is then reduced to ethanol by an alcohol dehydrogenase called ADH1. The purpose of this latter step is the regeneration of NAD+, so that the energy-generating glycolysis can continue. Humans exploit this process to produce alcoholic beverages, by letting yeast ferment various fruits or grains. It is interesting to note that yeast can produce and consume their own alcohol.

The main alcohol dehydrogenase in yeast is larger than the human one, consisting of four rather than just two subunits. It also contains zinc at its catalytic site. Together with the zinc-containing alcohol dehydrogenases of animals and humans, these enzymes from yeasts and many bacteria form the family of "long-chain"-alcohol dehydrogenases.

Brewer's yeast also has another alcohol dehydrogenase, ADH2, which evolved out of a duplicate version of the chromosome containing the ADH1 gene. ADH2 is used by the yeast to convert ethanol back into acetaldehyde, and it is only expressed when sugar concentration is low. Having these two enzymes allows yeast to produce alcohol when sugar is plentiful (and this alcohol then kills off competing microbes), and then continue with the oxidation of the alcohol once the sugar, and competition, is gone.[17]

Plants

In plants, ADH catalyses the same reaction as in yeast and bacteria to ensure that there is a constant supply of NAD+.Maize has two versions of ADH - ADH1 and ADH2, Arabidopsis thaliana contains only one ADH gene. The structure of Arabidopsis ADH is 47% conserved, relative to ADH from horse liver, structurally and functionally important residues, such as the seven residues that provide ligands for the catalytic and noncatalytic zinc atoms, however are conserved suggesting that the enzymes have a similar structure.[18] ADH is constitutively expressed at low levels in the roots of young plants grown on agar, if the roots lack oxygen, the expression of ADH increases significantly.[19] It's expression is also increased in response to dehydration, low temperatures and to abscisic acid and it plays an important role in fruit ripening, seedling and pollen development.[20] Differences in the sequences of ADH in different species have been used to create phylogenies showing how closely related different species of plants are.[21] It is an ideal gene to use due to its convenient size (2-3 kb in length with a ~1000 nucleotide coding sequence) and low copy number.[20]

Iron-containing

A third family of alcohol dehydrogenases, unrelated to the above two, are iron-containing ones. They occur in bacteria, and an apparently inactive form has also been found in yeast.[citation needed] In comparison to enzymes the above families, these enzymes are oxygen-sensitive.

Other types

A further class of alcohol dehydrogenases belongs to quinoenzymes and requires quinoid cofactors (e.g., pyrroloquinoline quinone, PQQ) as enzyme-bound electron acceptors. A typical example for this type of enzyme is methanol dehydrogenase of methylotrophic bacteria.

Applications

In fuel cells, alcohol dehydrogenases can be used to catalyze the breakdown of fuel for an ethanol fuel cell. Scientists at Saint Louis University have used carbon-supported alcohol dehydrogenase with poly(methylene green) as an anode, with a nafion membrane, to achieve about 50 μA/cm2.[22]

In biotransformation, alcohol dehydrogenases are often used for the synthesis of enantiomerically pure stereoisomers of chiral alcohols. In contrast to the chemical process, the enzymes yield directly the desired enatiomer of the alcohol by reduction of the corresponding ketone.

Clinical significance

Alcoholism

There have been studies showing that ADH may have an influence on the dependence on ethanol metabolism in alcoholics. Researchers have tentatively detected a few genes to be associated with alcoholism. If the variants of these genes encode slower metabolizing forms of ADH2 and ADH3, there is increased risk of alcoholism. The studies have found that mutations of ADH2 and ADH3 are related to alcoholism in Asian populations. However, research continues in order to identify the genes and their influence on alcoholism.[23]

Drug dependence

Drug dependence is another problem associated with ADH, which researchers think might be linked to alcoholism. One particular study suggests that drug dependence has seven ADH genes associated with it. These results may lead to treatments that target these specific genes. However, more research is necessary.[24]

See also

References

  1. ^ PDB: 1m6h​; Sanghani PC, Robinson H, Bosron WF, Hurley TD (2002). "Human glutathione-dependent formaldehyde dehydrogenase. Structures of apo, binary, and inhibitory ternary complexes". Biochemistry. 41 (35): 10778–86. doi:10.1021/bi0257639. PMID 12196016. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  2. ^ a b Danielsson O, Jörnvall H (1992). ""Enzymogenesis": classical liver alcohol dehydrogenase origin from the glutathione-dependent formaldehyde dehydrogenase line". Proc. Natl. Acad. Sci. U.S.A. 89 (19): 9247–51. doi:10.1073/pnas.89.19.9247. PMC 50103. PMID 1409630. {{cite journal}}: Unknown parameter |month= ignored (help)
  3. ^ a b Persson B, Hedlund J, Jörnvall H (2008). "Medium- and short-chain dehydrogenase/reductase gene and protein families : the MDR superfamily". Cell. Mol. Life Sci. 65 (24): 3879–94. doi:10.1007/s00018-008-8587-z. PMC 2792335. PMID 19011751. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  4. ^ Negelein E, Wulff HJ (1937)). Biochem. Z. 293: 351. {{cite journal}}: Check date values in: |year= (help); Missing or empty |title= (help)CS1 maint: year (link)
  5. ^ Theorell H, McKee JS (1961). "Mechanism of action of liver alcohol dehydrogenase". Nature. 192: 47–50. doi:10.1038/192047a0. PMID 13920552. {{cite journal}}: Unknown parameter |month= ignored (help)
  6. ^ Jörnvall H, Harris JI (1970). "Horse liver alcohol dehydrogenase. On the primary structure of the ethanol-active isoenzyme". Eur. J. Biochem. 13 (3): 565–76. doi:10.1111/j.1432-1033.1970.tb00962.x. PMID 5462776. {{cite journal}}: Unknown parameter |month= ignored (help)
  7. ^ Brändén CI, Eklund H, Nordström B, Boiwe T, Söderlund G, Zeppezauer E, Ohlsson I, Akeson A (1973). "Structure of liver alcohol dehydrogenase at 2.9-angstrom resolution". Proc. Natl. Acad. Sci. U.S.A. 70 (8): 2439–42. doi:10.1073/pnas.70.8.2439. PMC 433752. PMID 4365379. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  8. ^ Hellgren M (2009). Enzymatic studies of alcohol dehydrogenase by a combination of in vitro and in silico methods, Ph.D. thesis (PDF). Stockholm, Sweden: Karolinska Institutet. p. 70. ISBN 978-91-7409-567-8.
  9. ^ a b Sofer W, Martin PF (1987). "Analysis of alcohol dehydrogenase gene expression in Drosophila". Annual Review of Genetics. 21: 203–25. doi:10.1146/annurev.ge.21.120187.001223. PMID 3327463.
  10. ^ a b c d Hammes-Schiffer S, Benkovic SJ (2006). "Relating protein motion to catalysis". Annual Review of Biochemistry. 75: 519–41. doi:10.1146/annurev.biochem.75.103004.142800. PMID 16756501.
  11. ^ Erik G. Brandt, Mikko Hellgren, Tore Brinck, Tomas Bergman and Olle Edholm (2009). "Molecular dynamics study of zinc binding to cysteines in a peptide mimic of the alcohol dehydrogenase structural zinc site". Phys. Chem. Chem. Phys. (PCCP). 11 (6): 975–83. doi:10.1039/b815482a. PMID 19177216.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ Sultatos LG, Pastino GM, Rosenfeld CA, Flynn EJ (2004). "Incorporation of the genetic control of alcohol dehydrogenase into a physiologically based pharmacokinetic model for ethanol in humans". Toxicological Sciences : an Official Journal of the Society of Toxicology. 78 (1): 20–31. doi:10.1093/toxsci/kfh057. PMID 14718645. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  13. ^ http://www.medicinenet.com/alcohol_and_nutrition/article.htm
  14. ^ Duester, G. (2008) Retinoic acid synthesis and signaling during early organogenesis. Cell 134: 921-931. PMCID: PMC2632951
  15. ^ Parlesak A, Billinger MH, Bode C, Bode JC (2002). "Gastric alcohol dehydrogenase activity in man: influence of gender, age, alcohol consumption and smoking in a caucasian population". Alcohol and Alcoholism (Oxford, Oxfordshire). 37 (4): 388–93. doi:10.1093/alcalc/37.4.388. PMID 12107043.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  16. ^ Cox, Michael; Nelson, David R.; Lehninger, Albert L (2005). Lehninger principles of biochemistry. San Francisco: W.H. Freeman. p. 180. ISBN 0-7167-4339-6.{{cite book}}: CS1 maint: multiple names: authors list (link)
  17. ^ Coghlan A (2006-12-23). "Festive special: The brewer's tale - life". New Scientist. Retrieved 2009-04-27. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  18. ^ C Chang and E M Meyerowitz (1986-03-01). "Molecular cloning and DNA sequence of the Arabidopsis thaliana alcohol dehydrogenase gene — PNAS". Proceedings of the National Academy of Sciences of the United States of America. 83 (5). Pnas.org: 1408–12. PMC 323085. PMID 2937058. Retrieved 2010-07-04.
  19. ^ Chung, Hwa-Jee (October). "Arabidopsis Alcohol Dehydrogenase Expression in Both Shoots and Roots Is Conditioned by Root Growth Environment". Plant Physiology. 121 (2): 429–436. doi:10.1104/pp.121.2.429. PMC 59405. PMID 10517834. {{cite journal}}: Check date values in: |date= and |year= / |date= mismatch (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  20. ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1007/s00894-009-0576-0, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1007/s00894-009-0576-0 instead.
  21. ^ Jarvinen, P.; Palme, A.; Orlando Morales, L.; Lannenpaa, M.; Keinanen, M.; Sopanen, T.; Lascoux, M. "Phylogenetic relationships of Betula species (Betulaceae) based on nuclear ADH and chloroplast matK sequences - Järvinen et al. 91 (11): 1834 - American Journal of Botany". American Journal of Botany. 91. Amjbot.org: 1834. doi:10.3732/ajb.91.11.1834. Retrieved 2010-07-04.
  22. ^ Moore CM, Minteer SD, Martin RS (2005). "Microchip-based ethanol/oxygen biofuel cell". Lab on a Chip. 5 (2): 218–25. doi:10.1039/b412719f. PMID 15672138. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  23. ^ Sher KJ, Grekin ER, Williams NA (2005). "The development of alcohol use disorders". Annual Review of Clinical Psychology. 1: 493–523. doi:10.1146/annurev.clinpsy.1.102803.144107. PMID 17716097.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  24. ^ Luo X, Kranzler HR, Zuo L, Wang S, Schork NJ, Gelernter J (2007). "Multiple ADH genes modulate risk for drug dependence in both African- and European-Americans". Human Molecular Genetics. 16 (4): 380–90. doi:10.1093/hmg/ddl460. PMC 1853246. PMID 17185388. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  • PDBsum has links to three-dimensional structures of various alcohol dehydrogenases contained in the Protein Data Bank
  • ExPASy contains links to the alcohol dehydrogenase sequences in Swiss-Prot, to a Medline literature search about the enzyme, and to entries in other databases.
  • Radio Free Genome created a musical score from a sequence of alcohol dehydrogenase. MP3 audio version and an open source version of the software used to create it is available.