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NSE is the ?? isoform of the glycolytic enzyme enolase and is expressed primarily in neurons, in normal and neoplastic neuroendocrine cells. NSE is a highly soluble cytoplasmic protein that is readily secreted into the CSF and serum following tissue damage. NSE shows neurotrophic and neuroprotective properties on a broad spectrum of central nervous system (CNS) neurons and binds in a calcium-dependent manner to cultured neocortical neurons promoting cell survival.

MGMT is an enzyme that repairs O-6-methylguanine, a mutagenic DNA base damaged by endogenous and environmental alkylating agents and takes part in the cellular defense against the biological effects of O-6-methylguanine in DNA. MGMT repairs alkylated guanine in DNA by stoichiometrically transferring the alkyl group at the O-6 position to a cysteine residue in the enzyme. abnormal MGMT expression correlates with the prognosis in human solid cancers. MGMT decrease of expression is correlated with methylation. The human MGMT is a negative regulator of estrogen receptor-mediated transcription upon alkylation DNA damage. MGMT promoter hypermethylation plays an important role in the early steps of colorectal carcinogenesis. Abnormal promoter hypermethylation of MGMT gene is associated with oral squamous cell carcinomas.

Methionine sulfoxide reductase B (MsrB) from Escherichia coli is a member of the msrB Met sulfoxide reductase family. The E.coli msrB carries out the reduction of methionine-R-sulfoxide to methionine. msrB possess a metal binding site composed of 2 CXXC motifs. The bound metal (zinc or iron) may stabilize the conformation of the enzymes.

Hexokinases phosphorylate glucose to produce glucose-6-phosphate, thus committing glucose to the glycolytic pathway. Hexokinase 2 is the predominant form found in skeletal muscle. It localizes to the outer membrane of mitochondria. Expression of this gene is insulin-responsive, and studies in rat suggest that it is involved in the increased rate of glycolysis seen in rapidly growing cancer cells.

AKR7A3, takes part in the detoxification of aldehydes and ketones. AKR7A3 reduces the dialdehyde protein-binding form of aflatoxin B1 (AFB1) to the non-binding AFB1 dialcohol. AKR7A3 participates in protection of liver against the toxic and carcinogenic effects of AFB1, a potent hepatocarcinogen.

ALKBH2 is a member of the ALKB family.ALKBH2 is expressed in the heart, colon, liver, testis, ovary, prostate and the small intestine. ALKBH2 uses iron as a cofactor and acts as a dioxygenase which catalyzes the repair of alkylated DNA and RNA containing 1-methyladenine and 3-meth-ylcytosine. ALKBH2 is functionally activated by ascorbate and requires oxygen and ?-ketoglutarate for enzymatic activity.

NUDT9 is a member of a superfamily of Nudix hydrolases. NUDT9 functions as a highly specific adenosine diphosphate ribose pyrophosphatase which hydrolyzes ADP ribose to AMP and ribose 5'-phosphate. In addition, NUDT9 may be involved in the regulation of the menstrual cycle and may be related to the proliferation of glandular cells in the human endometrium.

L-threonine to glycine degradation consists of a two-step biochemical pathway which involvs the enzymes L-threonine dehydrogenase and 2-amino-3-ketobutyrate coenzyme A ligase. L-Threonine is initially converted into 2-amino-3-ketobutyrate by L-threonine dehydrogenase. Glycine C-Acetyltransferase (GCAT) is the 2nd enzyme in this pathway, which subsequently catalyzes the reaction between 2-amino-3-ketobutyrate and coenzyme A to form glycine and acetyl-CoA. The GCAT enzyme is regard as a class II pyridoxal-phosphate-dependent aminotransferase. GCAT is strongly expressed in the heart, brain, liver and pancreas. GCAT is also found in lung.

Antioxidant enzyme Glutathione S- Transferase (GST) is thought to do the primary cellular defense mechanism against reactive oxygen species. GST reduces lipid hydroperoxides through its Se-independent glutathione peroxidase activity. The enzyme also detoxifies lipid peroxidation end products such as 4-hydroxynonenal (4-HNE).
The soluble GST is a 26 kDa protein which occurs as a dimer in all aerobic organisms. Each monomer has two domains, one that binds GSH and is an /-structure similar to thioredoxin and the other, all helical, that binds the hydrophobic substrate. The GST -fusion protein expression system is a widely used recombinant protein expression system that allows a peptide or a regulatory protein domain to be expressed as a fusion to the C-terminus of Schistosoma japonicum GST. Fusion proteins also possess GST -enzymatic activity and can undergo dimerization similar to in vivo. The fusion protein can be purified via GST -affinity column chromatography. In most cases, the desired peptides or domains are removed from GST by applying a specific protease that recognizes and cleaves the linker between the protein domain and GST. The technique has been widely used to generate different kinds of proteins for crystallization, molecular immunology studies, the production of vaccines and studies involving protein-protein and protein-DNA interactions.

Ectonucleoside Triphosphate Diphosphohydrolase 3, also known as ENTPD3, which owns a threefold preference for the hydrolysis of ATP over ADP is similar to E-type nucleotidases (NTPases). ENTPD3 is a protein coding gene which contains four apyrase-conserved areas which is characteristic of NTPases.

Sepiapterin Reductase is an aldo-keto reductase that catalyzes the NADPH-dependent reduction of pteridine derivatives and is essential in the biosynthesis of BH4. Mutations in Sepiapterin Reductase gene result in DOPA-responsive dystonia due to sepiaterin reductase deficiency defined by the presence of sustained involuntary muscle contractions, often leading to abnormal postures. Sepiapterin reductase is part of the short-chain dehydrogenase/reductase family which reduces exogenous carbonyl compounds as well as phenylpropanedione. Sepiapterin reductase is an important enzyme for the biosynthesis of tetrahydrobiopterin, an necessary cofactor for aromatic amino acid hydrolases together with tyrosine hydroxylase, the rate-limiting enzyme in DOPA synthesis.

Sulfite oxidase, also known as SUOX is a homodimeric protein localized to the intermembrane space of mitochondria. Each subunit includes a heme domain as well as a molybdopterin-binding domain. The SUOX enzyme catalyzes the oxidation of sulfite to sulfate, the last reaction in the oxidative degradation of the sulfur amino acids cysteine and methionine. In addition, the deficiency of SUOX results in neurological abnormalities which are often fatal at an early age.

TXNRD1 belongs to the selenium-containing pyridine nucleotide-disulphide oxidoreductase family, which has a conserved catalytic site of Cys-Val-Asn-Val-Gly-Cys. TXNRD1 decreases thioredoxins as well as other substrates, and participates in selenium metabolism and protection against oxidative stress. Inhibition of TXNRD1 activity serves as a potential treatment for cancer, AIDS and other autoimmune diseases as well as bacterial infections and parasitic diseases.

AHCY is an enzyme that catalyzes the reversible hydrolysis of S-adenosylhomocysteine (AdoHcy) to adenosine (Ado) and L-homocysteine (Hcy). AHCY controls the intracellular S-adenosylhomocysteine (SAH) concentration that is crucial for transmethylation reactions. AHCY deficiency causes hypermethioninemia.

Alanine aminotransferase 2 (GPT2), catalyzes the reversible transamination among alanine and 2-oxoglutarate to create pyruvate and glutamate. GPT2 expressed mainly in muscle, fat and kidney and participates in the intermediary metabolism of glucose and amino acids. Multiple transcript variants encoding various isoforms have been found for GPT2.

F-ATPase delta (ATP5D) catalyzes ATP synthesis, employing an electrochemical gradient of protons across the inner membrane during oxidative phosphorylation. ATP synthase is composed of 2 linked multi-subunit complexes: F1-the soluble catalytic core and Fo- the membrane-spanning component, which comprise the proton channel. The catalytic portion of mitochondrial ATP synthase consists of five different subunits (alpha, beta, gamma, delta, and epsilon) assembled with a stoichiometry of 3 alphas, 3 betas, and a single representative of the other three. The proton channel consists of three main subunits-a, b, c. ATP5D is the delta subunit of the catalytic core.

AKR7A2 participates in the detoxification of aldehydes and ketones. AKR7A2 catalyzes the NADPH-dependent reduction of succinic semialdehyde to gamma-hydroxybutyrate. AKR7A2 is involved in producing the neuromodulator gamma-hydroxybutyrate (GHB). AKR7A2 has extensive substrate specificity. AKR7A2 shows NADPH-dependent aldehyde reductase activity towards 2-carboxybenzaldehyde, 2-nitrobenzaldehyde and pyridine-2-aldehyde (in vitro). AKR7A2 reduces 1,2-naphthoquinone and 9,10-phenanthrenequinone (in vitro). AKR7A2 reduces the dialdehyde protein-binding form of aflatoxin B1 (AFB1) to the non-binding AFB1 dialcohol. AKR7A2 takes part in protection of liver against the toxic and carcinogenic effects of AFB1, a potent hepatocarcinogen.

Formiminotransferase cyclodeaminase is an enzyme which catalyzes the conversion of formiminoglutamateand tetrahydrofolateinto formiminotetrahydrofolateand glutamate.
Formiminotransferase cyclodeaminase, a bifunctional enzyme of tetrahydrofolate synthesis, is the target antigen of anti-LC1 (liver cytosol antigen type 1) autoantibodies. Presence of LC1 autoantibodies is a marker for type 2 autoimmune hepatitis (for which anti-LKM 1/cytochrome P450 2D6 autoantibodies are a further marker).
Serum LC1 autoantibody concentrations appear to fluctuate in parallel with aminotransferase levels, a particularly intriguing observation that suggests a possible role of LC1 autoreactivity in the pathogenic mechanism leading to hepatocyte injury.

Glutathione S-transferase or GST, stands for a large family of detoxification proteins and enzymes. Glutathione S-transferase catalyzes glutathione reaction and an acceptor molecule to create S-substituted glutathione (S stands for sulfur). By this reaction, a large variety of compounds, for example therapeutic drugs, carcinogens & oxidative stress products, transformed. Glutathione S-transferase acts as a transport protein by binding toxins and acts as a transport protein. At first, the protein was isolated from Schistosomajaponicum, nowadays it is isolated from E. coli bacteria.

Magnesium-dependent phosphatase 1 (MDP1) is a memeber of the HAD-like hydrolase superfamily. MDP1 is a magnesium-dependent phosphatase which may act as a tyrosine phosphatase. MDP1 is inhibited by vanadate and zinc, and slightly by calcium.

P450 Oxidoreductase, also known as POR is a flavoprotein which contributes electrons to all microsomal P450 enzymes. POR is localized to the endoplasmic reticulum, where it is also capable of transfering electrons to heme oxygenase as well as cytochrome b5. POR is structurally related to two separate flavoprotein families; first one is ferredoxin nucleotide reductase and the second flavodoxin.

Alanine transaminase or ALT is a transaminaseenzyme.
ALT is found in serumand in various bodily tissues, but is most commonly associated with the liver; It catalyzes the transfer of an aminogroup from alanineto a-ketoglutarate, the products of this reversible transaminationreaction being pyruvateand glutamatealanine+ a-ketoglutarate= pyruvate+ glutamate
It is commonly measured clinically as a part of a diagnostic liver function test, to determine liver health. It is also called serum glutamate pyruvate transaminase (SGPT) or alanine aminotransferase (ALAT). Diagnostically, it is almost always measured in units/litre (U/L).

Phosphoglycerate mutase 2 (PGAM2) is a member of the phosphoglycerate mutase family. PGAM is a dimeric enzyme which contains in separate tissues, different proportions of a slow-migrating muscle (MM) isozyme, a fast-migrating brain (BB) isozyme, and a hybrid form (MB). PGAM (Phosphoglycerate mutase) catalyzes the reversible reaction of 3-phosphoglycerate (3-PGA) to 2-phosphoglycerate (2-PGA) in the glycolytic pathway. PGAM2 gene mutations cause muscle phosphoglycerate mutase efficiency, otherwise known as glycogen storage disease X.

N-alpha-acetyltransferase 50 (NAA50) consists of 169 amino acid cytoplasmic protein belonging to the acetyltransferase family and GNAT subfamily. NAA50 is a likely catalytic component of the ARD1A-NARG1 complex which displays alpha acetyltransferase activity. NAA50 has also been shown to interact with MAK10 and is encoded by a gene that maps to human chromosome 3q13.2.