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 nicotinamide adenine dinucleotide (NAD+) to NADH. In humans and many other animals, they serve to break down alcohols that are otherwise toxic, and they also participate in the generation of useful aldehyde, ketone, or alcohol groups during the 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+.
Acetaldehyde dehydrogenases are dehydrogenase enzymes which catalyze the conversion of acetaldehyde into acetyl-CoA. This can be summarized as follows:
Ethanol, an alcohol found in nature and in alcoholic drinks, is metabolized through a complex catabolic metabolic pathway. In humans, several enzymes are involved in processing ethanol first into acetaldehyde and further into acetic acid and acetyl-CoA. Once acetyl-CoA is formed, it becomes a substrate for the citric acid cycle ultimately producing cellular energy and releasing water and carbon dioxide. Due to differences in enzyme presence and availability, human adults and fetuses process ethanol through different pathways. Gene variation in these enzymes can lead to variation in catalytic efficiency between individuals. The liver is the major organ that metabolizes ethanol due to its high concentration of these enzymes.
Aldehyde dehydrogenase, mitochondrial is an enzyme that in humans is encoded by the ALDH2 gene located on chromosome 12. ALDH2 belongs to the aldehyde dehydrogenase family of enzymes. Aldehyde dehydrogenase is the second enzyme of the major oxidative pathway of alcohol metabolism. ALDH2 has a low Km for acetaldehyde, and is localized in mitochondrial matrix. The other liver isozyme, ALDH1, localizes to the cytosol.
Trifunctional enzyme subunit alpha, mitochondrial also known as hydroxyacyl-CoA dehydrogenase/3-ketoacyl-CoA thiolase/enoyl-CoA hydratase, alpha subunit is a protein that in humans is encoded by the HADHA gene. Mutations in HADHA have been associated with trifunctional protein deficiency or long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency.
Alcohol dehydrogenase 1B is an enzyme that in humans is encoded by the ADH1B gene.
Alcohol dehydrogenase 1C is an enzyme that in humans is encoded by the ADH1C gene.
Aldo-keto reductase family 1 member C3 (AKR1C3), also known as 17β-hydroxysteroid dehydrogenase type 5 is a key steroidogenic enzyme that in humans is encoded by the AKR1C3 gene.
Aldo-keto reductase family 1 member C1 also known as 20α-hydroxysteroid dehydrogenase, 3α-hydroxysteroid dehydrogenase, and dihydrodiol dehydrogenase 1/2 is an enzyme that in humans is encoded by the AKR1C1 gene.
Aldehyde dehydrogenase, dimeric NADP-preferring is an enzyme that in humans is encoded by the ALDH3A1 gene.
Alcohol dehydrogenase 4 is an enzyme that in humans is encoded by the ADH4 gene.
3α-Hydroxysteroid dehydrogenase is an enzyme that in humans is encoded by the AKR1C4 gene. It is known to be necessary for the synthesis of the endogenous neurosteroids allopregnanolone, THDOC, and 3α-androstanediol. It is also known to catalyze the reversible conversion of 3α-androstanediol (5α-androstane-3α,17β-diol) to dihydrotestosterone and vice versa.
Isocitrate dehydrogenase [NAD] subunit gamma, mitochondrial is an enzyme that in humans is encoded by the IDH3G gene.
Alcohol dehydrogenase class 4 mu/sigma chain is an enzyme that in humans is encoded by the ADH7 gene.
Isocitrate dehydrogenase [NAD] subunit beta, mitochondrial is an enzyme that in humans is encoded by the IDH3B gene.
Aldehyde dehydrogenase X, mitochondrial is an enzyme that in humans is encoded by the ALDH1B1 gene.
4-trimethylaminobutyraldehyde dehydrogenase is an enzyme that in humans is encoded by the ALDH9A1 gene.
Alcohol dehydrogenase 6 is an enzyme that in humans is encoded by the ADH6 gene.
Aldehyde dehydrogenase family 3 member B2 is an enzyme that in humans is encoded by the ALDH3B2 gene.
Aldehyde dehydrogenase 3 family, member B1 also known as ALDH3B1 is an enzyme that in humans is encoded by the ALDH3B1 gene.
