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TOP1 is an important nuclear enzyme that interconverts supercoiled DNA to the necessary topological conformations for standard DNA replication and transcription. TOP1 is the target antigen for TOP1 autoantibodies. TOP1 antibodies are a specific marker in scleroderma patients (specificity 98-100%) and are related with the existence of diffuse skin involvement and pulmonary fibrosis. In human tissues top1 enzyme is primarily synthesized as a protein with a molecular weight of 100-kDa. Most of this precursor is then proteolytically processed to a 70-kDa size, from which the TOP1 antigen has derived its name.

CNDP Dipeptidase 1, also known as CNDP1 is a member of the peptidase M20A family. CNDP1 Mannheim which is the shortest allelic form has been more common in the absence of nephropathy in addition to being associated with lower serum carnosinase levels. Furthermore, Carnosine inhibited the increased production of fibronectin as well as collagen type VI in podocytes and the increased production of TGF-beta in mesangial cells. Diabetic patients with the CNDP1 Mannheim variant are less at risk for nephropathy. In addition, on renal cells carnosine protects against the adverse effects of high glucose levels.

Poly (ADP-Ribose) Polymerase 2 (PARP2) contains a catalytic domain which is homologous to that of poly (ADP-ribosyl) transferase but lacks an N-terminal DNA binding domain which activates the C-terminal catalytic domain of poly (ADP-ribosyl) transferase. PARP2 is capable of catalyzing a poly (ADP-ribosyl)ation reaction. The basic residues within the N-terminal area of this protein can bear potential DNA-binding properties, and can be engaged in the nuclear and/or nucleolar targeting of the protein. There has been found two alternatively spliced transcript variants encoding distinct isoforms.

Epoxide Hydrolase 1 Microsomal (EPHX1) is a vital biotransformation enzyme which transfers epoxides from the degradation of aromatic compounds to trans-dihydrodiols that can be conjugated and excreted from the body. Epoxide hydrolase plays a role in both activation and detoxification of epoxides. Mutations in EPHX1 trigger preeclampsia, epoxide hydrolase deficiency or increased epoxide hydrolase activity.

CNDP Dipeptidase 2 (CNDP2), is a cytosolic, non-specific dipeptidase which is a part of the peptidase M20A protein family. CNDP2 is a secreted peptidase homologous to M20 peptidases. CNDP2 expresses through all adult and fetal tissue, though, an isoform missing exons 3 and 4 expresses in all fetal tissue in adult liver. Over expression of CPGL-B in hepatocellular carcinoma cells results in significant inhibition of HC cell viability, colony formation, cell invasiveness and tumor configuration.

Methionine aminopeptidases and designated peptidase M proteins belong to the M24 family of proteins. MAP protein removes the amino-terminal methionine residue from nascent polypeptides. The active site of MAP contains 2 adjacent divalent metal ions connected by a water molecule or hydroxide ion.

COMT catalyzes the transfer of a methyl group from S-adenosylmethionine (SAM) to catechol substrates such as the neurotransmitters. This O-methylation results in one of the main degradative pathways of the catecholamine transmitters. COMT COMT is located in the postsynaptic neuron and is involved in the metabolism of catechol estrogen drugs used in the treatment of hypertension, asthma, Parkinson disease and the inactivation of catecholamine neurotransmitters though enzymatic degradation. COMT appears in tissues in 2 forms, a soluble form and a membrane-bound form which differ in their N-termini. COMT inhibitors increase its availability and are used in the treatment of patients with Parkinson's disease.

Ribose-5-phosphate isomerase (RPIA) is a member of the ribose 5-phosphate isomerase family. RPIA is an enzyme which catalyzes the conversion between ribose-5-phosphate (R5P) and ribulose-5-phosphate (Ru5P). RPI occurs as 2 separate proteins forms, termed RPIA and RPIB. RPIA has a vital role in the metabolism of plants and animals, as it is involved in the Calvin cycle which takes place in plants, and the pentose phosphate pathway which occurs in plants as well as animals.

SURA is a PPIase enzyme and chaperone of Escherichia coli and other Gram-negative bacteria. SURA is a key player in the biogenesis of beta-barrel outer membrane proteins and is involved in cell envelope homeostasis and cell envelope functions. SURA is necessary for the survival of E.coli in stationary phase and needed for pilus biogenesis.

DCTD is an allosteric enzyme that exists as a homohexamer and is part of the cytidine and deoxycytidylate deaminase protein family. DTCD uses zinc as a cofactor to catalyze the deamination of dCMP to dUMP, thus making the nucleotide substrate (dUMP) that is used by thymidylate synthase.

DPP4 also called adenosine deaminase complexing protein-2, and T-cell activation antigen CD26 is a serine exopeptidase and complex enzyme that is expressed on the surface of most cell types. DPPIV is an intrinsic membrane glycoprotein and a serine exopeptidase that cleaves X-proline dipeptides from the N-terminus of polypeptides. DPP4 plays a role in t-cell activation. DPP4 is associated with intracellular signal transduction, apoptosis and involved in tumor biology. There are at least 63 substrates which can bind specifically to DPP4 enzyme including growth factors, chemokines, neuro peptides. Furthermore, DPP4 plays a major role in glucose metabolism by cleaving incretins such as glucose-dependent insulinotropic polypeptide (GIP) and GLP-1.

Isopentenyl-diphosphate isomerase 1 (IDI1) belongs to the IPP isomerase type I family and is involved in cholesterol biosynthesis. IDI1 is a peroxisomally-localized enzyme which catalyzes the interconversion of isopentenyl diphosphate (IPP) to its highly electrophilic isomer, dimethylallyl diphosphate (DMAPP), which is the substrate for the sequential reaction that results in the synthesis of farnesyl diphosphate and, eventually, cholesterol. Peroxisomal deficiency diseases such as Zellweger syndrome and neonatal adrenoleukodystrophy show a reduction in IPP isomerase activity.

Glutamyl endopeptidase (GLU-C) is an enzyme which cleaves peptide bonds on the carboxyl-terminal side of glutamic acid and, less frequently, aspartic acid (for example: Glu-|-Xaa, Asp-|-Xaa). GLU-C is a pathogenic factor involved in the adherence and colonization of human tissue. GLU-C preferentially cleaves peptide bonds on the carboxyl-terminal side of aspartate and glutamate. GLU-C is required for proteolytic maturation of thiol protease SspB and inactivation of SspC, an inhibitor of SspB. GLU-C is the most important protease for degradation of fibronectin-binding protein (FnBP) and surface protein A, which are involved in adherence to host cells. Furthermore, GLU-C protects bacteria against host defense mechanism by cleaving the immunoglobulin classes IgG, IgA and IgM. GLU-C may also be involved in the stability of secreted lipases.

HPSE also known as Heparanase-1 is an enzyme which cleaves heparan sulfate proteoglycans to allow cell movement through changing the extracellular matrix. In fact, the Heparan sulfate proteoglycans are major components of the basement membrane and extracellular matrix. In addition, this cleavage can release bioactive molecules from the extracellular matrix. HPSE is significant for the overall degradation of proteins in lysosomes.

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.

RNMT is a widely expressed nuclear protein which is a member of the mRNA cap methyltransferase family. Cap-dependent mRNA translation requires the methylation of the mRNA guanosine cap by RNMT. RNMT catalyzes the transfer of a methyl group from AdoMet (S-adenosylmethionine) to the GpppN end of the growing mRNA at the N-7 position, thus producing AdoHyc (S-adenosylhomocysteine) and m7GpppN terminated RNA.

PRMT1 Methylates (mono & asymmetric dimethylation) the guanidino nitrogens of arginyl residues present in a glycine and arginine-rich domain (may methylate HNRNPA1 and histones). Methylates SUPT5H.
The PRMT1 protein functions as a histone methyltransferase specific for H4.
PRMT1 is an essential factor in oncogenesis and is a potential novel therapeutic target in cancer.
PRMT1-mediated methylation serves as a positive modulator of IR/IRS-1/PI3K pathway and glucose uptake in skeletal muscle cells.
CAF1 is a new regulator of PRMT1-dependent arginine methylation.
PRMT1 arginine-methylates MRE11 therefore it regulates the activity of MRE11-RAD50-NBS1 complex during the intra-S-phase DNA damage checkpoint response.
PRMT1 plays a post-translationally part in regulating the transcriptional activity.
PRMT1is found predominantly in the cytoplasma though a fraction of PRMT1 is located in the nucleus.

METTL21A, which is a part of the methyltransferase superfamily, is a Protein-lysine methyltransferase that in vitro methylates HSPA1, HSPA5 and HSPA8.

Methionine aminopeptidase 1 (METAP1) is a member of the peptidase M24A family. METAP1 removes the amino-terminal methionine from nascent proteins. METAP1 releases N-terminal amino acids, preferentially methionine, from peptides and arylamides. METAP1 is essential for normal progression through the cell cycle. The active site of METAP1 contains 2 adjacent divalent metal ions linked by a water molecule or hydroxide ion.

Matrix metalloproteinases are a family of zinc and calcium-dependent endopeptidases that break down extracellular matrix proteins. The MMP9 is secreted as a 92kDa zymogen. Cleavage of ProMMP-9 results in the active enzyme, having a molecular weight of approximately 82kDa. MMP9 is composed of the following domains: a gelatin-binding domain consisting of three fibronectin type II units, a catalytic domain containing the zinc-binding site, a proline-rich type V collagen-homologous domain and a hemopexin-like domain. MMP9 is produced by the several cell types: monocytes, macrophages, neutrophils, keratinocytes, fibroblasts, osteoclasts and endothelial cells. MMP9 is involved in inflammatory responses, tissue remodeling, wound healing, tumor growth and metastasis. MMP9 may also play an important part in local proteolysis of the extracellular matrix and in leukocyte migration, as well as in bone osteoclastic resorption. MMP9 cleaves type IV and type V collagens into large C-terminal three quarter fragments and shorter N-terminal one quarter fragments. MMP9 can also degrade fibronectin but not laminin or Pz-peptide.
MMP9 defects may be a cause of susceptibility to intervertebral disc disease (IDD), also known as lumbar disk herniation (LDH).

CNDP Dipeptidase 1, also known as CNDP1 is a member of the peptidase M20A family. CNDP1 Mannheim which is the shortest allelic form has been more common in the absence of nephropathy in addition to being associated with lower serum carnosinase levels. Furthermore, Carnosine inhibited the increased production of fibronectin as well as collagen type VI in podocytes and the increased production of TGF-beta in mesangial cells. Diabetic patients with the CNDP1 Mannheim variant are less at risk for nephropathy. In addition, on renal cells carnosine protects against the adverse effects of high glucose levels.

Dopachrome Tautomerase also known as DCT, belongs to the tyrosinase family. DCT takes a significant part in the synthesis of the melanin pigment including tyrosinase (Tyr), tyrosinase-related protein 1 (Tyrp1). Which are highly involved in eumelanin synthesis. The change among the eumelanin and the pheomelanin pathways is assumed to depend on the presence of cysteine. Hence, in the lack of cysteine, dopaquinone, the product of tyrosinase action, is transformed to cyclodopa (leucodopachrome) and afterwards to dopachrome (and DOPA).