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Dihydroorotate dehydrogenase quinone (DHODH) is a member of the dihydroorotate dehydrogenase family. DHODH is a mitochondrial protein found on the outer surface of the inner mitochondrial membrane. DHODH catalyzes the 4th enzymatic step, the ubiquinone-mediated oxidation of dihydroorotate to orotate (with quinone as electron acceptor), in de novo pyrimidine biosynthesis. DHODH gene defects cause the postaxial acrofacial dysostosis (POADS), also known as Miller syndrome.

N-Acetylgalactosaminidase Alpha (NAGA) is a lysosomal exoglycosidase which removes terminal alpha-N-acetylgalactosamine residues from glycopeptides and glycolipids. NAGA is necessary for the breakdown of glycolipids.

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.

Carboxypeptidase B (EC 3.4.17.2) catalyzes hydrolysis of the basic amino acids lysine, arginine and ornithine from the C-terminal end of polypeptides. The Mw was found to be 34.5 kDa, optimun pH-7.9, and pI-6. Carboxypeptidase B is inhibited by arginine, lysine and ornithine. The enzyme is not inhibited by di-isopropylfluorophosphate (DFP), but it is inhibited by metal chelating agents, e.g., EDTA, 1,10-phenanthroline.

DESI1 belongs to the DeSI family and contains 1 PPPDE peptidase domain. This protein is a protease which deconjugates SUMO1, SUMO2 and SUMO3 from some substrate proteins and has isopeptidase but not SUMO-processing activity. DESI1 desumoylates ZBTB46.

Dehydrogenase/reductase SDR family member 4 (DHRS4) is a member of the short-chain dehydrogenases/reductases (SDR) family. DHRS4 reduces all trans retinal and 9-cis retinal. In addition, the DHRS4 protein can catalyze the oxidation of all trans retinol with NADP as cofactor, but with a much lower efficiency. Furthermore, DHRS4 reduces alkyl phenyl ketones and alpha dicarbonyl compounds with aromatic rings, such as pyrimidine 4 aldehyde, 3 benzoylpyridine, 4 benzoylpyridine, menadione and 4 hexanoylpyridine.

HEXA is the alpha subunit of the lysosomal enzyme beta-hexosaminidase which, combined with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules having N-acetyl hexosamines terminus. The two subunits composing Beta-hexosaminidase, alpha and beta, belong to the glycosyl hydrolases family and are encoded by distinct genes. Alpha subunit gene mutations can cause Tay-Sachs disease (GM2-gangliosidosis type I).

Matrix metalloproteinase-2 (MMP-2) is a type IV collagenase, which is involved in endometrial menstrual breakdown, regulation of vascularization and the inflammatory response. MMP-2 contains a number of distinct domains: a prodomain that is cleaved upon activation; a catalytic domain containing the zinc binding site; a fibronectin like domain believed to have a role in substrate targeting; and a carboxyl terminal (hemopexin like) domain containing 2 N-linked glycosylation. The MMP-2 can degrade an extensive array of substrates including type IV, V, VII and X collagens as well as gelatin type I. In addition, MMP-2 interacts with THBS2, TIMP2, Thrombospondin 1, CCL7 and TIMP4. MMP-2 autocatalytic cleavage in the C-terminal generates the anti-angiogenic peptide, PEX. This process seems to be made possible by binding integrinv/beta3. Defects in the MMP-2 are the cause of Torg-Winchester syndrome (TWS), aka multicentric osteolysis nodulosis and arthropathy (MONA).

Carbonic anhydrases (CAs) are a large family of zinc metalloenzymes which catalyze the reversible hydration of carbon dioxide. These metalloenzymes participate in various biological processes, including respiration, calcification, acid-base balance, bone resorption, and the formation of aqueous humor, cerebrospinal fluid, saliva, and gastric acid. The metalloenzymes exhibit extensive diversity in tissue distribution and in their subcellular localization. Carbonic Anhydrase XI (CA11) is probably a secreted protein, nevertheless, drastic changes at active site residues completely conserved in CA isozymes with catalytic activity, make it unlikely that CA11 has carbonic anhydrase activity. CA11 shares properties in common with 2 other acatalytic CA isoforms, CA VIII and CA X. CA11 is amply expressed in the brain, and may have a general role in the central nervous system.

Fumarase is an enzymatic factor of Krebs cycle, which catalyzes the formation of L-malate from fumarate. Fumarase exists in both a cytosolic form and an N-terminal extended form, differing only in the translation start site used. The N-terminal extended form is aimed to the mitochondrion, where the removal of the extension results in the same form as in the cytoplasm. Fumarase is similar to a number of thermostable Class-2 fumarases and functions as a homotetramer. Mutations in the Fumarase gene causes fumarase deficiency and leads to progressive encephalopathy, cerebral atrophy and developmental delay. Fumarase enzyme is also thought to act as a tumor suppressor. Leydig cell tumors are caused by Fumarase mutations and represents one of the first reports of germline mutations in any type of adult testicular tumor.

Glutamate-cysteine ligase (GCLM) is the first rate limiting enzyme of glutathione synthesis. The GCLM enzyme is comprised of 2 subunits, a heavy catalytic subunit and a light regulatory subunit. GCLM deficiency is associated with some forms of hemolytic anemia.

GPT catalyzes the reversible transamination between alanine and 2-oxoglutarate to create pyruvate and glutamate. GPT has a crucial part in the intermediary metabolism of glucose and amino acids. GPT is broadly used as an indicator of liver reliability or hepatocellular destruction in clinical tests.

Glutathione S-transferase, also known as GST, is an antioxidant enzyme. It is the primary defense mechanism from reactive oxygen in the cell. The enzyme GST reduces hydroperoxides of lipids via a Se-independent glutathione peroxidase actions. GST detoxifies peroxidation of lipids bi-products, for example 4-hydroxynonenal.

ATP-dependent Clp protease proteolytic subunit (CLPP) is a member of the peptidase family S14. CLPP cleaves peptides in a variety of proteins in a manner which requires ATP hydrolysis. CLPP being the catalytic core of the Clp proteolytic complex is commonly involved in many cellular processes via the regulation of intracellular protein quality. CLPP is responsible for a somewhat general and central housekeeping function rather than for the degradation of specific substrates.

UBE2T is part of the E2 ubiquitin-conjugating enzyme family that participates in the protein degradation pathway. UBE2T catalyzes the ATP-dependent attachment of ubiquitin to target proteins, thus tagging them for subsequent destruction by the proteasome. UBE2T is an important factor of the Faconi anemia pathway of DNA damage repair and, upon self-inactivation, may negatively regulate the Faconi pathway.

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.

UBE2V2 comprises a distinct subfamily within the E2 protein family. They have sequence similarity to other ubiquitin-conjugating enzymes however require the conserved cysteine residue that is vital for the catalytic activity of E2s. UBE2V2 shares homology with ubiquitin-conjugating enzyme E2 variant 1 and yeast MMS2 gene product. UBE2V2 participates in the differentiation of monocytes and enterocytes.

Monoamine Oxidase A, also known as MAOA catalyzes the oxidative deamination of biogenic as well as xenobiotic amines and has significant functions in the metabolism of neuroactive and vasoactive amines in the central nervous system as well as peripheral tissues. Mutation in MAOA results in Brunner syndrome; in addition MAOA has also been linked with a diversity of other psychiatric disorders, which includes antisocial behavior. MAOA preferentially oxidizes biogenic amines such as 5-hydroxytryptamine (5-HT).

Luciferase is a general term for the class of oxidative enzymes used in bioluminescence and is distinct from a photoprotein. Luciferase catalyzes a bioluminescent reaction which involves the substrate luciferin as well as Mg2+ and ATP, produces green light with a wavelength of 562 nm. Luciferase from firefly is broadly used as a reporter for studying gene regulation and function, and for pharmaceutical screening.

Beta-1,3-glucuronyltransferase 3 (B3GAT3) is involved in forming the linkage tetrasaccharide present in heparan sulfate and chondroitin sulfate. B3GAT3 has a part in the biosynthesis of l2/HNK-1 carbohydrate epitope on glycoproteins. B3GAT3 shows strict specificity for Gal-beta-1,3-Gal-beta-1,4-Xyl, exhibiting negligible incorporation into other galactoside substrates including Galbeta1-3Gal beta1-O-benzyl, Galbeta1-4GlcNAc and Galbeta1-4Glc.

NT5M is a member of the 5'(3')-deoxyribonucleotidase family. NT5M localizes to the mitochondrial matrix. The NT5M enzyme dephosphorylates the 5'- and 2'(3')-phosphates of uracil and thymine deoxyribonucleotides. The NT5M gene is located on chromosome 17 p11.2 in the critical region deleted in the Smith-Magenis syndrome (SMS), a genetic disease of unidentified etiology.

DAAO is a peroxisomal enzyme which uses FAD (flavin adenine dinucleotide) as a cofactor and oxidizes D-amino acids to the corresponding amino acids, producing ammonia and hydrogen peroxide. DAAO substrates include an extensive array of D-amino acids, but it is inactive on the naturally occurring L-amino acids. DAAO acts on a variety of D-amino acids especially on those having small hydrophobic side chains followed by those bearing polar, aromatic, and basic groups; however it doesn’t act on acidic amino acids. DAAO may be involved in acid base balance in the kidney or it could act as a detoxifying agent which removes D-amino acids accumulated during aging. DAAO regulates the neuromodulator D-serine level in the brain. DAAO is highly active towards D-DOPA. Creatinine inhibits the DAAO in uremia. DAAO may also have a role in the pathophysiology of schizophrenia, but not in bipolar disorder.

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.

ACAT2 enzyme participates in lipid metabolism. ACAT2 takes part in lipoprotein assembly, catalyzing cholesterol esterification in mammalian cells. ACAT2 is an integral membrane protein that localizes to the endoplasmic reticulum of human intestinal cells. ACAT2 deficiency contributes to severe mental retardation and hypotonus.