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Listeriolysin O (aka LLO) is a hemolysin produced by Listeria monocytogenes bacteria, the pathogen responsible for causing listeriosis. The toxin may be regarded as a virulence factor, since it is crucial for the virulence of L. monocytogenes. LLO is a single polypeptide protein encoded by the hlyA gene and composed of 529 residues. LLO is a thiol-activated cholesterol-dependent pore forming toxin protein; therefore, it is activated by reducing agents and inhibited by oxidizing agents. Still, LLO differs from other thiol-activated toxins, as its cytolytic activity is maximized at a pH of 5.5. Inside the acidic phagosomes (average pH ~ 5.9) of cells that have phagocytosed L. monocytogenes, LLO is selectively activated by maximizing activity at a pH of 5.5. Following the phagosome lysis by LLO, the bacterium breaks out into the cytosol, where it is able to grow intracellularly, and the toxin has reduced activity in the more basic cytosol. Thus, LLO permits L. monocytogenes to break out from the phagosomes into the cytosol without harming the plasma membrane of the infected cell, which allows the bacteria to live intracellularly, where they are sheltered from extracellular immune system factors such as the complement system and antibodies. LLO also brings about dephosphorylation of histone H3 and deacetylation of histone H4 in the early phases of infection, before entry of L. monocytogenes into the host cell. The pore-forming activity is not implicated in causing the histone modifications. The modifications of the histones affect the down regulation of genes encoding proteins involved in the inflammatory response. Therefore, LLO may be significant in subverting the host immune response to L. monocytogenes. At its NH2-terminus it possesses a 25 residues long typical signal sequence excited during the secretion process. Moreover, in its NH2-terminus there is also a 19 amino acids PEST- like sequence that may target this toxin for degradation. The PEST-like sequence found in LLO and is considered crucial for virulence, given that mutants lacking the sequence lysed the host cell. Nevertheless, contrary to PEST's supposed role in protein degradation, evidence implies that the PEST-like sequence may control LLO production in the cytosol rather than increase degradation of LLO.

Heparanase is an endo β-D-glucuronidase, which degrades heparan sulfate side chains of heparan sulfate proteoglycans (HSPGs) in the extracellular matrix. Heparanase plays an important role in ECM degradation, facilitating the migration and extravasation of tumor cells and inflammatory leukocytes (1,2,3). Upon degradation, heparanase releases growth factors and cytokines that stimulate cell proliferation and chemotaxis (4,5). Heparanase is a heterodimer comprised of a 50 kDa subunit harboring the active site and a 8 kDa subunit. It is produced as a latent 65 kDa precursor and proteolytically processed to its active form (1,6). Heparanase is highly expressed in myeloid leukocytes (i.e. neutrophils) in platelets and in human placenta. Human heparanase was found to be upregulated in various types of primary tumors, correlating in some cases with increased tumor invasiveness and vascularity and with poor prospective survival (7,8).

ST6GAL1 also known as ST6 Beta-Galactosamide Alpha-2,6-Sialyltranferase 1, is part of the glycosyltransferase family 29. ST6GAL1 is a type II membrane protein which catalyzes the transfer of sialic acid from CMP-sialic acid to galactose-containing substrates. Furthermore, ST6GAL1 is normally found in the Golgi however it can be proteolytically processed to a soluble form, ST6GAL1 is also involved in the generation of the cell-surface carbohydrate determinants as well differentiation antigens HB-6, CD75, and CD76.

BPNT1 belongs to the magnesium-dependent, lithium-sensitive phosphomono-esterase superfamily. BPNT1 catalyzes the conversion of PAPS (adenosine 3'-phosphate 5' phosphosulfate) to APS (adenosine 5'-phosphosulfate) and the conversion of PAP (3'(2')-phosphoadenosine 5' phosphate) to AMP (adenosine 5'-phosphate) using magnesium as a cofactor. BPNT1 is expressed everywhere but at maximum levels in brain and kidney. BPNT1 is potently inhibited by lithium, a drug used for the treatment of manic depression and bipolar affective disorder, which suggests that BPNT1 has a possible role in the etiology of mood disorders.

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.

Hexokinases phosphorylate glucose to produce glucose-6-phosphate, thus committing glucose to the glycolytic pathway. Hexokinase1 encodes a ubiquitous form of hexokinase which localizes to the outer membrane of mitochondria. Mutations in this gene have been associated with hemolytic anemia due to hexokinase deficiency. Alternative splicing of HXK1 results in five transcript variants which encode different isoforms, some of which are tissue-specific. Each isoform has a distinct N-terminus; the remainder of the protein is identical among all the isoforms. A sixth transcript variant has been described, but due to the presence of several stop codons, it is not thought to encode a protein.

Deoxyribose-phosphate aldolase (DERA) is a member of the deoC/fbaB aldolase protein family involved in the carbohydrate degradation pathway. DERA catalyzes the conversion of 2-deoxy-D-ribose 5-phosphate to D-glyceraldehyde 3-phosphate and an acetyldehyde.

Napsin A Aspartic Peptidase, also known as NAPSA is a member of the peptidase A1 family. NAPSA is involved in the processing of pneumocyte surfactant precursors. Furthermore the activation peptides of aspartic proteinases take part as inhibitors of the active site. These peptide segments/pro-parts are considered essential for correct folding, targeting, as well as control of the activation of aspartic proteinase zymogens. The pronapsin A gene is expressed mostly in lung and kidney. In addition, NAPSA translation product is expected to be a fully functional, glycosylated aspartic proteinase precursor which contains an RGD motif as well as an additional 18 residues at its C-terminus.

Hyaluronidase-1 or HYAL1 is a protein, part of the endolytic glycoside hydrolase proteins group. Human hyaluronidases proteins, are 5 endo­β­N­acetyl­hexosaminidases (including HYAL1, HYAL2, HYAL3). Hyaluronidase-1 causes degradation to hyaluronic acid in the extracellular matrix of somatic tissues. HYAL1 needs an acidic environment and is the most common hyaluronidase in the plasma. Mutations in this protein can lead to mucopolysaccharidosis type IX and hyaluronidase deficiency.

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.

Ectonucleotide Pyrophosphatase (ENPP1) belongs to the ecto-nucleotide pyrophosphatase/phosphodiesterase (ENPP) family. ENPP1 is a type II transmembrane glycoprotein comprised of 2 identical disulfide-bonded subunits. The ENPP1 protein has broad specificity and cleaves various substrates, including phosphodiester bonds of nucleotides and nucleotide sugars and pyrophosphate bonds of nucleotides and nucleotide sugars. The ENPP1 protein can hydrolyze nucleoside 5' triphosphates to their corresponding monophosphates and it may also hydrolyze diadenosine polyphosphates. ENPP1 gene mutations are linked with 'idiopathic' infantile arterial calcification and ossification of the posterior longitudinal ligament of the spine (OPLL).

Beta-Glucocerebrosidase, also known as GBA is amember of the glycosyl hydrolase 30 family. GBA is a lysosomal enzyme which requires a signal peptide for transport across the membrane of the rough endoplasmic reticulum as well as glycosylation for transport into lysosomes. Furthermore, Gaucher disease is caused by a deficiency in the activity of the enzyme glucocerebrosidase.

Tissue plasminogen activator (abbreviated PLAT or tPA) is a secreted serine proteasewhich converts the proenzymeplasminogento plasmin, a fibrinolyticenzyme. Plasminogen is synthesized as a single chain which is cleaved by PLAT into the two chain disulfide linked plasmin.
This enzyme plays a role in cell migrationand tissue remodeling. Increased enzymatic activity causes hyperfibrinolysis, which manifests as excessive bleeding; decreased activity leads to hypofibrinolysiswhich can result in thrombosisor embolism.

Alpha-galactosidase A (GLA) is a homodimeric glycoprotein which hydrolyses the terminal alpha-galactosyl moieties from glycolipids and glycoproteins. GLA catalyzes the hydrolysis of melibiose into galactose and glucose. Various mutations in the GLA gene affect the synthesis, processing, and stability of this enzyme, which causes Fabry disease (a rare lysosomal storage disorder which results from a failure to catabolize alpha-D-galactosyl glycolipid moieties).

PRTN3 is a polymorphonuclear leukocyte serine protease which degrades elastin, fibronectin, laminin, vitronectin, and collagen types I, III, and IV (in vitro) and causes emphysema once managed by tracheal insufflation to hamsters.

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.

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).

Aldolase C Fructose-Bisphosphate (ALDOC) belongs to the class I fructose-bisphosphate aldolase family. ALDOC is a glycolytic enzyme which catalyzes the reversible aldol cleavage of fructose-1,6-biphosphate and fructose 1-phosphate to dihydroxyacetone phosphate and either glyceraldehyde-3-phosphate or glyceraldehydes respectively. ALDOC is expressed exclusively in the hippocampus and Purkinje cells of the brain.

The enzyme horseradish peroxidase, found in horseradish, is used extensively in molecular biologyand in antibody amplification and detection, among other things. For example, "In recent years the technique of marking neurons with the enzyme horseradish peroxidase (HRP) has become a major tool. In its brief history, this method has probably been used by more neurobiologists than have used the Golgi stainsince its discovery in 1870." Horseradish peroxidase is also highly used in techniques such as Western blottingand ELISAs.
HRP is widely used as an enzymatic label in immunoassays. Usually, the enzyme is coupled to antibodies, lectins or haptens. Coupling to antibodies etc. may be performed through the carbohydrate side chains of the HRP.

Arylsulfatase A (ARSA) hydrolyzes cerebrosidesulfate to cerebroside and sulfate. ARSA is inhibited by phosphate. The phosphate develops a covalent bond with the active site 3-oxoalanine. ARSA gene defects cause metachromatic leucodystrophy (MLD), a progressive demyelination disease which results in various neurological symptoms and ultimately death.

Neuron-specificenolase also caled NSE is a glycolytic isoenzyme which is situated in central and peripheral neurons and neuroendocrine cells. Enolase-2 is released into the CSF when neural tissue is injured. Neoplasms derived from neural or neuroendocrine tissue release Enolase-2 into the blood. Enolase-2 is a useful substance that has been detected in patients with certain tumors, such as neuroblastoma, small cell lung cancer, medullary thyroid cancer, carcinoid tumors, pancreatic endocrine tumors, and melanoma. ENO2 is 1 of the 3 enolase isoenzymes found in mammals. ENO2 isoenzyme, is found in mature neurons and cells of neuronal origin. An exchange from alpha enolase to gamma enolase occurs in neural tissue during development in rats and primates.

ST6GAL1 also known as ST6 Beta-Galactosamide Alpha-2,6-Sialyltranferase 1, is part of the glycosyltransferase family 29. ST6GAL1 is a type II membrane protein which catalyzes the transfer of sialic acid from CMP-sialic acid to galactose-containing substrates. Furthermore, ST6GAL1 is normally found in the Golgi however it can be proteolytically processed to a soluble form, ST6GAL1 is also involved in the generation of the cell-surface carbohydrate determinants as well differentiation antigens HB-6, CD75, and CD76.

Beta-galactosidase or GLB1 is a B-galactosidase found in the lysosome. This enzyme hydrolyzes the finale B-galactose from the precursors ganglioside & keratin sulfate. GLB1 has a crucial part in the creation of elastogenesis (extracellular elastic fibers) and connective tissue development. This enzyme is similar to elastin-binding protein which is a key part in non-integrin cell surface receptor. In cells that extort elastin GLB1 is linked to tropoelastin intracellularly and act as recycling molecular chaperone.