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Lysyl Oxidase also known as LOX is an extracellular copper enzyme which initiates the crosslinking of collagens and elastin. LOX catalyzes oxidative deamination of the epsilon-amino group in certain lysine and hydroxylysine residues of collagens and lysine residues of elastin. Adding up to crosslinking extracellular matrix proteins, LOX plays a part in tumor suppression. Moreover, defects in LOX are the cause of autosomal recessive cutis laxa type I, CL type I. Two transcript variants encoding dissimilar isoforms have been found for LOX.

Celiac disease is an enteropathy that is characterized by intestinal lesions of variable severity. Tissue-type transglutaminase (tTG) is believed to be the predominant autoantigen for celiac disease and the corresponding autoantibodies show higher sensitivity and specificity than anti-gliadin antibodies. Highly pure recombinant human tTG is now available to replace the traditionally used tTG fraction from guinea pig.
Tissue-type transglutaminase antigens have been specifically modified for improved handling: exchange of an active site amino acid eliminates the protein cross-linking activity of the enzyme, while maintaining the native three-dimensional structure and the enzyme's secondary GTPase activity. This engineering assures reproducible properties of the antigen preparations through the absence of variable and ill-defined covalent aggregates of tTG antigen and host cell proteins.

GLUL catalyzes the synthesis of glutamine from glutamate and ammonia. Glutamine is a major source of energy and that takes part in cell proliferation, inhibition of apoptosis, and cell signaling. GLUL is expressed during early fetal stages, and has a role in maintaining body pH by removing ammonia from circulation. Mutations in GLUL gene are related with congenital glutamine deficiency.

GSTZ1 is part of the glutathione S-transferase super-family which encodes multifunctional enzymes vital in the detoxification of electrophilic molecules, including carcinogens, mutagens, and several therapeutic drugs, by conjugation with glutathione. GSTZ1 participates in the catabolism of phenylalanine and tyrosine. Thus defects in GSTZ1 cause harsh metabolic disorders including alkaptonuria, phenylketonuria and tyrosinaemia. GSTZ1 is a bifunctional protein which has minimal glutathione-conjugating activity with 7-chloro-4-nitrobenz-2-oxa-1,3-diazole and maleylacetoacetate isomerase activity. GSTZ1 has low glutathione peroxidase activity with T-butyl and cumene hydroperoxides. GSTZ1 catalyzes the glutathione dependent oxygenation of dichloroacetic acid to glyoxylic acid.

Acetylcholinesterase (ACHE) belongs to the type-B carboxylesterase/lipase family. ACHE catalyzes the breakdown of acetylcholine and other choline esters that play a role as neurotransmitters. During neurotransmission, ACH is released from the presynaptic neuron into the synaptic cleft and binds ACH receptors on the post-synaptic membrane, transmitting the signal from the nerve. ACHE is located on the post-synaptic membrane, terminates the signal transmission by hydrolyzing ACH.

Cathepsin F ( CTSF) is a member of the peptidase C1 family. Cathepsins are papain familycysteine proteinases which are a main component of the lysosomal proteolytic system. The CTSF gene isubiquitously expressed, and it maps to chromosome 11q13, close to the gene encoding cathepsin W. CTSF plays a role in normal protein catabolism. CTSF involved in some degradative processes occurring in tumor progression since it is highly expressed in some cancer cell lines.

Ribonuclease 3 (RNASE3) is cytotoxin and helminthotoxin with low-efficiency ribonuclease activity. RNASE3 possesses a broad diversity of biological activities. RNASE3 protein has shown antibacterial activity such as cytoplasmic membrane depolarization of preferentially Gram-negative and Gram-positive strains and promotes E. coli outer membrane detachment, alteration of the overall cell shape and partial loss of cell content.

Histamine N-Methyltransferase or HNMT, is located in the cell cytosol. Sadenosyl-L-methionine acts as a methyl donor for HNMT which inactivates histamine. By inactivation of histamine, it affects the immune system’s response. HNMT acts on histamine in body tissues such as kidney, central nervous system and bronchus. The protein has a crucial part in the airway response to histamine & histamine degradation process and regulation.

Sialidase 1 (NEU1) is a lysosomal enzyme which cleaves terminal sialic acid residues from substrates such as glycoproteins and glycolipids. In the lysosome, the NEU1 enzyme is part of a heterotrimeric complex in cooperation with beta-galactosidase and cathepsin A. NEU1 gene mutations may lead to sialidosis, a lysosomal storage disease that can be the type 1 (cherry red -myoclonus syndrome or normosomatic type), which is late-onset, or the type 2 (the dysmorphic type), which takes place at an earlier age with increased acuteness.

Thymine-DNA glycosylase (TDG) is a member of the TDG/mug DNA glycosylase family.
TDG is a nuclear protein that fixes G/T mismatches to G/C pairs by hydrolyzing the carbon-nitrogen bond between the sugar-phosphate backbone of the DNA and the mispaired thymin. In addition, TDG removes uracil and 5-bromouracil from mispairings with guanine. The TDG enzyme has an essential role in cellular defense against genetic mutation triggered by the spontaneous deamination of 5-methylcytosine and cytosine.

Arginase-1 is part of the urea cycle, it catalyzes the hydrolysis of arginine to ornithine and urea. There are two isoforms of mammalian arginase which differ in their tissue location, subcellular localization, immunologic crossreactivity & physiologic role. Arginase-1is a cytosolic enzyme and expressed primarily in the liver tissue. Inherited deficiency in this enzyme may lead toargininemia, which is an autosomal recessive disease in which hyperammonemia is detected.

Ribonuclease 7 (RNASE7) is one of the final RNase A superfamily ribonucleases. RNASE7 was isolated from skin-derived stratum corneum. RNASE7 protein demonstrated potent ribonuclease activity and hence may contribute to the well-known ribonuclease activity of human skin. RNASE7 has revealed a broad spectrum antimicrobial activity against many pathogenic microorganisms and extraordinarily potent activity.

HIBCH enzyme is in charge of hydrolysis of both HIBYL-CoA and beta-hydroxypropionyl-CoA. Damages in the HIBCH gene linked to 3-hyroxyisobutyryl-CoA hydrolase deficiency. Multiple transcript variants exist as a result of alternative splicing.

Cathepsin-Z (CTSZ) is a lysosomal cysteine proteinase and member of the peptidase C1 family. CTSZ, which has been also known as cathepsin X and cathepsin P, exhibits carboxy-monopeptidase and carboxy-dipeptidase activities. CTSZ is expressed ubiquitously in cancer cell lines and primary tumors and, similar to other members of this family, takes part in tumorigenesis.

Legumain, also known as LGMN, is a cysteine endopeptidase which demonstrates strict specificity for hydrolysis of asparaginyl bonds. Furthermore, LGMN can also cleave aspartyl bonds slowly, in particular under acidic conditions. LGMN plays an essential role in the endosomal/lysosomal degradation system as the Legumain deficiency causes the accumulation of pro cathepsins B, H & L, another group of lysosomal cysteine proteases. Furthermore, over expression of LGMN in tumors is important for invasion/metastasis.

OGG1 is a DNA glycosylase enzyme which takes part in base excision repair. OGG1 protein is the main enzyme accountable for the excision of 7,8-dihydro-8-oxoguanine (8-oxoG), a mutagenic base byproduct which arises as a result of exposure to reactive oxygen species (ROS). OGG1 shows beta lyase activity that nicks DNA 3'' to the lesion.

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).

Thyroid Peroxidase (TPO) represents one of the main autoantigenic targets in autoimmune thyroid disease of humans. Its identity with the formerly so-called `microsomal antigen` has been shown several years ago. As an integral membrane glycoprotein it is restricted to the apical plasma membrane of the follicular epithelial cells and comprises two identical subunits of approx. 100 kDa molecular weight. The hemoprotein TPO plays a key role in the thyroid hormone biosynthesis by catalysing both the iodination of tyrosyl residues and the coupling of iodotyrosyl residues in thyroglobulin (TG) to form precursors of the thyroid hormones T4 and T3.

Legumain, also known as LGMN is a lysosomal cysteine protease which is found in all mouse tissues, however it was mainly abundant in the kidney as well as placenta. LGMN plays an essential role in the endosomal/lysosomal degradation system as the Legumain deficiency causes the accumulation of pro cathepsins B, H & L, another group of lysosomal cysteine proteases. Furthermore, over expression of LGMN in tumors is important for invasion/metastasis.

Dimethylglycine oxidase (DMGO) is a covalent flavoenzyme from Arthrobacter globiformis that catalyzes the oxidative demethylation of dimethylglycine to yield sarcosine, formaldehyde, and hydrogen peroxide. The N-terminal region binds FAD covalently so it is yellowish.

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.

N-acetylneuraminate lyase (NanA) is a member of a family of lyases, specifically the oxo-acid-lyases, which cleave carbon-carbon bonds. NanA catalyzes the cleavage of N-acetylneuraminic acid (sialic acid) to form pyruvate and N-acetyl-D-mannosamine. NanA is inhibited by reduction with NaBH4 in the presence of the substrate, which indicates that it belongs to the Schiff-base-forming Class I aldolases. NanA is strongly inhibited by Cu2+ ions, p-chloromercuribenzoate and N-bromosuccinimide, it is also inhibited competitively by the reaction product, pyruvate, and its structurally related compounds, dihydroxyacetone and DL-glyceraldehyde.

Endonuclease III (nth) is a DNA repair enzyme which has both DNA N-glycosylase activity and AP-lyase activity. The DNA N-glycosylase activity releases numerous damaged pyrimidines from DNA by cleaving the N-glycosidic bond and leaving an AP (apurinic/apyrimidinic) site. This AP-lyase activity cleaves the phosphodiester bond 3' to the AP site by a beta-elimination, thus leaving a 3'-terminal unsaturated sugar and a product with a terminal 5'-phosphate.

ACO1 has a part in an iron sensor. ACO1 catalyzes the stereo-specific isomerization of citrate to isocitrate via cis-aconitate in the tricarboxylic acid cycle, a non-redox-active process.