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Lactate dehydrogenase (LDH) is an enzyme(EC1.1.1.27) present in a wide variety of organisms, including plants and animals.
A tetrameric enzyme that catalyses the interconversion of pyruvateand lactate with concomitant interconversion of NADH and NAD+. At high concentrations of pyruvate, the enzyme exhibits feedback inhibition and the rate of conversion of pyruvate to lactate is decreased. In vertebrates, genes for three different subunits (LDH-A, LDH-B and LDH-C) exist.

NADH Dehydrogenase Flavoprotein 2 (NDUFV2) is a 24 kDa Core subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I) which is a part of the minimal assembly required for catalysisthe. NDUFV2 is aslo involved in electron transfer. Mutations in NDUFV2 are implicated in Parkinson's disease, bipolar disorder, schizophrenia, and have been discovered in one case of early onset hypertrophic cardiomyopathy and encephalopathy.

MDH2 catalyzes the reversible oxidation of malate to oxaloacetate, utilizing the NAD/NADH cofactor system in the citric acid cycle. MDH2 is localized to the mitochondria and takes part in the malate-aspartate shuttle that functions in the metabolic coordination between cytosol and mitochondria. MDH2 is highy expressed in the adrenal system, small intestine, heart and pancreas.

NDUFS2 is a core subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I) which is a part of the minimal assembly required for catalysis. Complex I takes part in the transfer of electrons from NADH to the respiratory chain. Histidine NADH Dehydrogenase Fe-S Protein 2 (NDUFS2) is required for catalytic activity. Imperfections in NDUFS2 are the source of complex I mitochondrial respiratory chain deficiency, which is characterized by many symptoms including liver failure, cardiomyopathy and neurodegeneration.

D-lactate dehydrogenase (ldha) is a member of the D-isomer specific 2-hydroxyacid dehydrogenase family. In enzymology, an ldha (cytochrome) is an enzyme which catalyzes the chemical reaction. Therefore, the 2 substrates of the ldha enzyme are (D)-lactate and ferricytochrome c, whereas its 2 products are pyruvate and ferrocytochrome c.

NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 5 (NDUFA5) is a member of the complex I NDUFA5 subunit family. The human NDUFA5 gene codes for the B13 subunit of complex I of the respiratory chain that transfers electrons from NADH to ubiquinone. The NDUFA5 protein localizes to the inner mitochondrial membrane as part of the seven component-containing, water soluble 'iron-sulfur protein' (IP) fraction of complex I, even though its exact role is undetermined.

MDH1 catalyzes the reversible oxidation of malate to oxaloacetate, using the NAD/NADH cofactor system in the citric acid cycle. MDH1 is abundantly found in the cytoplasm and is involved in the malate-aspartate shuttle that functions in the metabolic coordination between cytosol and mitochondria. MDH1 regulates p53-dependent cell-cycle arrest and apoptosis in response to glucose deprivation.

Histidine NADH Dehydrogenase Fe-S Protein 5 (NDUFS5) belongs to the NADH dehydrogenase (ubiquinone) iron-sulfur protein family. NDUFS5 is a subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I), which doesn’t take part in catalysis. Complex I is transferring the electrons from NADH to the respiratory chain.

ACADS is a tetrameric mitochondrial flavoprotein, which is part of the acyl-CoA dehydrogenase family. ACADS catalyzes the first step of the mitochondrial fatty acid beta-oxidation pathway. Mutations in ACADS have been associated with Short Chain Acyl-CoA Dehydrogenase Deficiency.

MTHFD2 plays a role as a homodimer which requires magnesium and inorganic phosphate. MTHFD2 has a pseudogene on chromosome 7 and owns 3 different enzymatic activities. Each of the activities catalyzes 1 of 3 sequential reactions in the interconversion of 1-carbon derivatives of tetrahydrofolate, which are substrates for methionine, thymidylate, and de novo purine syntheses.

NDUFV3 is one of no less than 41 subunits which form the NADH-ubiquinone oxidoreductase complex that is involved in the mitochondrial respiratory chain and assists in catalyzing the rotenone-sensitive oxidation of NADH and the reduction of ubiquinone. NDUFV3 is 1 of 3 proteins found in the flavoprotein fraction of the complex but it exact function is unknown. Two transcript variants encoding altered isoforms are known for this gene.

ALDH2 is part of the aldehyde dehydrogenase family of proteins which catalyze the chemical transformation from acetaldehyde to acetic acid. ALDH2 is the second enzyme of the major oxidative pathway of alcohol metabolism. ALDH2 has 2 major liver isoforms: cytosolic and mitochondrial, which differ by their electrophoretic mobilities, kinetic properties, and subcellular localizations. Nearly all Caucasians have 2 major isozymes, whereas roughly 50% of Orientals have only the cytosolic isozyme, omitting the mitochondrial isozyme. The extremely higher rate of acute alcohol intoxication with Orientals compared to Caucasians is due to the fact of the absence of mitochondrial isozyme. ALDH2 has a low Km for acetaldehydes, and is localized in mitochondrial matrix.

HPGD is the essential enzyme of prostaglandin degradation. 15-PGDH protein strongly decreases the biologic activity of these molecules by catalyzing the oxidation of the 15-hydroxyl group of prostaglandins to a keto group. GDH1 is involved in numerous physiologic and cellular processes, for instance inflammation.

6PGD is the second dehydrogenase in the pentose phosphate shunt. Pentose is neccesary for nucleic acid biosynthesis. The pentose phosphate cycle is a major source of NADPH 6PGD deficiency is usually asymptomatic, and the inheritance of this disorder is autosomal dominant. PGD deficiency raises the erythrocyte pyruvate kinase levels of activity and decreases glutathione synthetase, resulting in hemolysis.

NQO1 belongs to the NAD(P)H dehydrogenase (quinone) family and encodes a cytoplasmic 2-electron reductase. NQO1 acts as an imperative part of cellular antioxidant defense by detoxifying quinines therefore preventing the formation of reactive oxygen species. It seems that NQO1 serves as a quinone reductase relating to conjugation reactions of hydroquinons involved in detoxification pathways in addition to biosynthetic processes such as the vitamin K-dependent gamma-carboxylation of glutamate residues in prothrombin synthesis. Altered NQO1 expression is seen in many tumors and also linked to Alzheimer’s disease. NQO1 gene mutations are linked to tardive dyskinesia which is an increased risk of hematotoxicity after exposure to benzene, and susceptibility to various forms of cancer.

Isocitrate dehydrogenase [NAD] subunit gamma (IDH3G) mitochondrial is a member of the isocitrate and isopropylmalate dehydrogenases family. Isocitrate dehydrogenases catalyze the oxidative decarboxylation of isocitrate to 2-oxoglutarate. The IDH3G is a gamma subunit of one isozyme of isocitrate dehydrogenase which belongs to a distinct subclass, which utilizes NAD(+) as the electron acceptor, and is restricted to the mitochondrial matrix.

NQO2 is a flavoprotein that catalyzes the 2-electron reduction of diverse quinones, redox dyes, and the vitamin K menadione. NQO2 mainly uses dihydronicotinamide riboside (NRH) as the electron donor. NQO2 catalyzes the metabolic detoxification of quinones and their derivatives to hydroquinones. This detoxification process protects cells against quinone-induced oxidative stress, cytotoxicity and mutagenicity.

Alcohol dehydrogenase 1A (ADH1A) is a member of the alcohol dehydrogenase family. ADH1A has a key role in ethanol metabolism. ADH1A along with coenzyme NAD catalyzes the reversible conversion of organic alcohols to ketones or aldehydes. The physiologic function of ADH1A in the liver is the elimination of ethanol formed by microorganisms in the intestinal tract. ADH1A is monomorphic and predominant in fetal and infant livers, growing to be less active in gestation and only weakly active during adulthood.

ALDH5A1 is a mitochondrial NAD(+)-dependent succinic semialdehyde dehydrogenase, which is a member of the aldehyde dehydrogenase family of proteins. The ALDH5A1 protein functions as a mediator to the NADP+-dependent oxidation of aldehydes into acids and has an imperative role in the detoxification of alcohol-derived acetaldehyde, as well as in lipid peroxidation and in the metabolism of corticosteroids, biogenic amines and neurotransmitters. ALDH5A1 is expressed in various tissues, including the liver, heart, lung, brain, kidney and placenta. Deficiency in the ALDH5A1 enzyme, known as 4-hydroxybutyricaciduria, is a rare inborn error in the metabolism of the neurotransmitter 4-aminobutyric acid (GABA). In response to this defect, physiologic fluids from patients accumulate GHB, which is a compound with numerous neuromodulatory properties.

GAPDH is a catalytic enzyme normally known to play a role in glycolysis. GAPDH exists as a tetramer composed of 36-kDa subunits and has a range of intracellular functions. GAPDH catalyzes the reversible reduction of 1,3-bisphosphoglycerate to glyceraldehyde 3-phosphophate in the presence of NADPH. Besides functioning as a glycolytic enzyme in cytoplasm, GAPDH has function in intracellular processes such as membrane fusion, microtubule bundling, phosphotransferase activity, nuclear RNA export, DNA replication and DNA repair. GAPDH catalyzes a vital energy-yielding step in carbohydrate metabolism, the reversible oxidative phosphorylation of glyceraldehyde-3-phosphate in the presence of inorganic phosphate and nicotinamide adenine dinucleotide (NAD). The enzyme exists as a tetramer of identical chains.

NADH Dehydrogenase1 Alpha Subcomplex 4 (NDUFA4) is a member of the complex I 9kDa subunit family. Mammalian complex I of mitochondrial respiratory chain is comprised of 45 different subunits. NDUFA4 protein has NADH dehydrogenase activity and oxidoreductase activity. NDUFA4 transfers electrons from NADH to the respiratory chain. The immediate electron acceptor for the NDUFA4 enzyme is assumed to be ubiquinone.

GAPDH is a catalytic enzyme normally known to play a role in glycolysis. GAPDH exists as a tetramer composed of 36-kDa subunits and has a range of intracellular functions. GAPDH catalyzes the reversible reduction of 1,3-bisphosphoglycerate to glyceraldehyde 3-phosphophate in the presence of NADPH. Besides functioning as a glycolytic enzyme in cytoplasm, GAPDH has function in intracellular processes such as membrane fusion, microtubule bundling, phosphotransferase activity, nuclear RNA export, DNA replication and DNA repair. GAPDH catalyzes a vital energy-yielding step in carbohydrate metabolism, the reversible oxidative phosphorylation of glyceraldehyde-3-phosphate in the presence of inorganic phosphate and nicotinamide adenine dinucleotide (NAD). The enzyme exists as a tetramer of identical chains.

Alcohol dehydrogenase 6 (ADH6) belongs to the alcohol dehydrogenase family. Alcohol dehydrogenase family members metabolize a wide variety of substrates, including ethanol, retinol, other aliphatic alcohols, hydroxysteroids, and lipid peroxidation products. ADH6 is expressed in the stomach as well as in the liver, and it contains a glucocorticoid response element upstream of its 5’ UTR, which is a steroid hormone receptor binding site.

E2 17-beta-dehydrogenase 8 (HSD17B8) is a member of the short-chain dehydrogenases/reductases (SDR) family. In mice, the HSD17B8 protein is a 17-beta-hydroxysteroid dehydrogenase which can regulate the concentration of biologically active estrogens and androgens. HSD17B8 is preferentially an oxidative enzyme and inactivates E2, testosterone, and DHT. However, the HSD17B8 enzyme has some reductive activity and can synthesize E2 from E1. HSD17B8 may have a role in biosynthesis of fatty acids in mitochondria.