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Glutaminyl-Peptide Cyclotransferase, also known as QPCT is a member of the glutaminyl-peptide cyclotransferase family. QPCT is responsible for the biosynthesis of pyroglutamyl peptides. Furthermore, QPCT is partial against acidic and tryptophan residues adjacent to the N-terminal glutaminyl residue and a lack of importance of chain length following the second residue. QPCT catalyzes N-terminal pyroglutamate formation, also in vitro, it catalyzes pyroglutamate formation of N-terminally truncated form of APP amyloid-beta peptides [Glu-3]-beta-amyloid.

tRNA-splicing endonuclease subunit Sen15 (TSEN15) is a member of the SEN15 family. tRNA splicing is an essential process required for cell growth and division. TSEN15 is a subunit of the tRNA splicing endonuclease. TSEN15 cleaves pre-tRNA at the 5' and 3' splice sites to release the intron.

MGAT2 is an enzyme which takes part in the catalyzation of a crucial step in the reaction of oligomannose which converts to complex N-glycans. MGAT2 has three domains, classic to glycosyltransferase: short N-terminal cytoplasmic domain, a C-terminal catalytic domain and hydrophobic non-cleavable signal-anchor domain. The enzyme MGAT2 is encoded by the MGAT2 gene in humans. There are no introns in the DNA coding the gene, therefore mutations in the MGAT2 will result in carbohydrate-deficient glycoprotein syndrome, type II.

LDHA catalyzes the conversion of L-lactate and NAD to pyruvate and NADH in the final step of anaerobic glycolysis. LDHA is localized primarily in muscle tissue and is part of the lactate dehydrogenase family. Mutations in LDHA have been linked to exertional myoglobinuria. LDH1 is decreased in essential thrombocythemia. LDHA is induced through a non-genomic pathway of estrogen action. Reduction in LDH-A activity results in stimulation of mitochondrial respiration and decrease of mitochondrial membrane potential.

Staphylokinase (SAK) is a 136-amino acidenzymefrom Staphylococcus aureus. It is positively regulated by the "agr" gene regulator. It activates plasminogen, which in turn can degrade various host proteins during infection.

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.

Glutathione peroxidase 1 (GPX1) is a member of the glutathione peroxidase family, consisting of 8 identified glutathione peroxidases (Gpx1-8) in humans. Glutathione peroxidase serves in the detoxification of hydrogen peroxide, and is one of the most vital antioxidant enzymes in humans. The GPX1 is a component of the enzymatic antioxidant defense, preventing oxidative damage to DNA, proteins and lipids by detoxifying hydrogen and lipid peroxides which may contribute to prostate cancer development. GPX1 is one of only a small number of proteins known in higher vertebrates to contain selenocysteine, which occurs at the active site of glutathione peroxidase and is coded by the nonsense (stop) codon TGA. Furthermore, the GPX1 protein is characterized in a polyalanine sequence polymorphism in the N-terminal region, which includes 3 alleles with 5, 6 or 7 alanine (ALA) repeats in this sequence. The allele with 5 ALA repeats is significantly linked to breast cancer risk.

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.

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.

Matrix Metalloproteinase-13 (MMP-13) is an enzyme that is a member of the MMP extracellular protease family. Extracellular protease enzymes, by virtue of their broad substrate specificities1, play a role in both normal and disease states of tissue proliferation. Among the targets of MMP-13 are collagen, gelatin, entactin, pro-TNF-a, and chemokine SDF-11-4.
MMP-13 is found in its latent form as a 52-56 kDa glycosylated proenzyme. Upon cleavage the 22-46 kDa5 MMP-1 becomes active in extracellular matrix remodeling.
Because of the prominent role that MMP-1 plays in cell migration and metastasis, it is an important target for inhibition screening.

DIM1 dimethyladenosine transferase 1 homolog (DIMT1) is a member of the methyltransferase superfamily. The DIMT1 enzyme specifically dimethylates 2 adjacent adenosines in the loop of a conserved hairpin near the 3'-end of 18S rRNA in the 40S particle. DIMT1 is restricted to the nucleolus.

Kell blood group glycoprotein homolog or KEL, is an enzyme, part of the zinc endopeptidase of the neprilysin (NEP) group of proteins. KEL has a crucial part in the production of the potent bioactive ET-3, which also includes enzymes that are endothelin convertingenzymes (PEX, XCE, DINE &various NEP-like proteins). KEL uses a single disulfide bond to XK, a gated membranal transporter. The Kell antigen system that includes two proteins, is very crucial among blood group systems.

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.

Cytochrome b5 reductase 2 (CYB5R2) is involved in desaturation and elongation of fatty acids, cholesterol biosynthesis, drug metabolism, and, in erythrocyte, methemoglobin reduction. CYB5R2 is responsible for NADH-dependent lucigenin chemiluminescence in spermatozoa by reducing both lucigenin and 2-[4-iodophenyl]-3-[4-nitrophenyl]-5-[2,4-disulfophenyl]-2H tetrazolium monosodium salt (WST-1).

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.

Phosphoglucomutase-1 also known as PGM1 is a member of the phosphohexose mutase family. There are more than a few PGM isozymes, which catalyze the transfer of phosphate between the 1&6positions of glucose. In nearly all cell types, PGM1 isozymes predominate, representing around 90% of total PGM activity. It has been found that defects in PGM1 are the cause of glycogen storage disease type 14.

GNPNAT1 is a member of the GNA1 subfamily of the larger acetyltransferase family of proteins. GNPNAT1 is limited to the Golgi apparatus and the endosome. GNPNAT1 is vital for UDPGlcNAc biosynthesis pathway. GNPNAT1 catalyzes the synthesis of GlcNAc6P from AcCoA and GlcN6P, a step in the UDP-GlcNAc6P formation pathway.

Placental alkaline phosphatase (PLAP) is a membrane-associated siaglycoprotein enzyme normally present at high concentration in syncytiotrophoblasts within the placenta during the third trimester of gestation. The expression of PLAP was originally thought to be restricted to term placenta but a human PLAP-like variant has been described which shares more than 85% homology with PLAP itself. PLAP is expressed only in normal term placenta, endocervix and fallopian tube and also in ovarian and proximal gastrointestinal tumors. It is also commonly expressed in germ cell tumors and more recently described in seminomas.

Ribophorin 2 (RPN2) is a dolichyl-diphosphooligosaccharide protein glycosyltransferase subunit 2. The Ribophorin 2 protein is part of an N-oligosaccharyl transferase complex which links high mannose oligosaccharides to asparagine residues found in the Asn-X-Ser/Thr consensus motif of nascent polypeptide chains. RPN2 is analogous in sequence to the yeast oligosaccharyl transferase subunit SWP1.

DLAT gene encodes component E2 of the multi-enzyme pyruvate dehydrogenase complex (PDC). PDC is located in the inner mitochondrial membrane and catalyzes the conversion of pyruvate to acetyl coenzyme A. The protein product of this gene, dihydrolipoamide acetyltransferase, takes acetyl groups created by the oxidative decarboxylation of pyruvate and transfers them to coenzyme A. Dihydrolipoamide acetyltransferase is the antigen for antimitochondrial antibodies which are found in about 95% of patients with the autoimmune liver disease primary biliary cirrhosis (PBC). In patients who suffer from this illness, activated T lymphocytes attack and destroy epithelial cells in the bile duct where this protein is abnormally distributed and overexpressed. PBC ultimately leads to cirrhosis and liver failure. Mutations in DLAT are also a cause of pyruvate dehydrogenase E2 deficiency which causes primary lactic acidosis in infancy and early childhood.

Ornithine Aminotransferase is a mitochondrial enzyme which is an important factor that converts arginine and ornithine into the major excitatory and inhibitory neurotransmitters glutamate and GABA. Ornithine Aminotransferase mutations result in a deficiency that cause the autosomal recessive eye disease Gyrate Atrophy.

Glutathione reductase (GSR) belongs to the class-I pyridine nucleotide-disulfide oxidoreductase family. The GSR enzyme is a homodimeric flavoprotein and has a role in maintaining glutathione (GSH) in its reduced form by catalyzing the reduction of glutathione disulfide (GSSG): GSSG + NADPH + H+ ->2GSH + NADP+. In the majority of eukaryotic cells, GSR upholds the ratio of [GSH] / [GSSG], and partakes in quite a few critical functions such as the detoxification of reactive oxygen species as well as protein and DNA biosynthesis.

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.