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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.

Aldo-keto reductase family 1 member C1 or AKR1C1 is an enzyme, part of the aldo/keto reductase family that holds over 40 familiar proteins. AKR1C1 promotes the conversion of ketones & aldehydes to their alcohol forms by using cofactors such as NADH & NADPH. AKR1C1 promotes the progesterone reduction to its inactive molecule form 20-alpha-hydroxy-progesterone.

Lactate dehydrogenase (LDH) is an enzyme(EC1.1.1.27) present in a wide variety of organisms, including plants and animals.
A tetrameric enzyme that catalyses the interconversion of pyruvateand lactate with concomitant interconversion of NADH and NAD+. At high concentrations of pyruvate, the enzyme exhibits feedback inhibition and the rate of conversion of pyruvate to lactate is decreased. In vertebrates, genes for three different subunits (LDH-A, LDH-B and LDH-C) exist.

Adenosine Kinase is an abundant enzyme in mammalian tissues which catalyzes the transfer of the gamma-phosphate from ATP to adenosine, thus is as a regulator of concentrations of both extracellular adenosine and intracellular adenine nucleotides. Adenosine has extensive effects on the cardiovascular, nervous, respiratory, and immune systems and inhibitors of the enzyme take a crucial pharmacological part in growing intravascular adenosine concentrations and acting as anti-inflammatory agents.

Ketohexokinase catalyzes the phosphorylation of fructose to produce fructose-1-phosphate, resulting in the utilization of ATP and creation of AMP. Ketohexokinase commences initial step in the metabolism of dietary fructose and is a significant regulator of hepatic glucose metabolism. Ketohexokinase is found in liver, renal cortex, and small intestine. Its deficiency causes the benign hereditary metabolic disorder essential fructosuria, leading to fructose being excreted in the urine. Ketohexokinase-dependent metabolism of fructose induces proinflammatory mediators in proximal tubular cells. ketohexokinase plays an unknown physiologic function that remains intact in essential fructosuria. Ketohexokinase expression is reduceed in human clear cell type of renal cell carcinoma.

NNMT is part of the family of transferases, especially those transferring one-carbon group methyltransferases. NNMT is mostly expressed in the liver, and a lower expression is seen in the kidney, lung, skeletal muscle, placenta and heart. NNMT catalyzes the N-methylation of nicotinamide and other pyridines to form pyridinium ions. This activity is significant for biotransformation of many drugs and xenobiotic compounds. NNMT is accountable for the enzymatic activity which uses S-adenosyl methionine as the methyl donor. NNMT expression is related with tumor stage and DFS time in hepatocellular carcinoma cases. NNMT is a good candidate as a tumor marker of various kinds of cancers. NNMT serum levels have significance in the premature detection and in the management of patients with colorectal cancer.

HMOX1 cleaves the heme ring at the alpha methene bridge to form Biliverdin. Biliverdin is then converted to Bilirubin by Biliverdin reductase. In physiological state, the highest activity of HMOX1 is found in the spleen, where senescent erythrocytes are sequestrated and destroyed. Heme Oxygenase-1 is involved in the regulation of cardiovascular function and its adaptive response to a variety of stressors. HMOX1 is induced in the colon of ulcerative colitis. HMOX1 is found to overexpress with a higher extent of intraplaque angiogenesis implies a multi-faceted role for HMOX1 in modulating the progression of atherosclerosis. HMOX1 expression reduced LPS-stimulated secretion of MCP-1, IL-6, IL-10, and TNF-alpha in murine and human macrophages.

STYX is a member of the protein-tyrosine phosphatase family. STYX has a Gly residue instead of a conserved Cys residue in the dsPTPase catalytic loop which renders it catalytically inactive as a phosphatase. Nevertheless, the binding pocket is adequately preserved to bind phosphorylated substrates, and possibly protect them from phosphatases. STYX takes part in spermiogenesis.

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.

DTD2 is e member of the DTD family. DTD2 protein hydrolyzes D-tyrosyl-tRNA(Tyr) into D-tyrosine and free tRNA(Tyr) as a defense mechanism against a harmful effect of D-tyrosine.

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.

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.

ALDH2 is part of the aldehyde dehydrogenase family of proteins which catalyze the chemical transformation from acetaldehyde to acetic acid. ALDH2 is the second enzyme of the major oxidative pathway of alcohol metabolism. ALDH2 has 2 major liver isoforms: cytosolic and mitochondrial, which differ by their electrophoretic mobilities, kinetic properties, and subcellular localizations. Nearly all Caucasians have 2 major isozymes, whereas roughly 50% of Orientals have only the cytosolic isozyme, omitting the mitochondrial isozyme. The extremely higher rate of acute alcohol intoxication with Orientals compared to Caucasians is due to the fact of the absence of mitochondrial isozyme. ALDH2 has a low Km for acetaldehydes, and is localized in mitochondrial matrix.

Acid phosphatase, prostate (ACPP) is a non-specific tyrosine phosphatase, which dephosphorylates a varied number of substrates under acidic conditions (pH 4-6) including alkyl, aryl, and acyl orthophosphate monoesters and phosphorylated proteins. ACPP has lipid phosphatase activity and inactivates lysophosphatidic acid in seminal plasma.

Chitinase 3-Like 2 (CHI3L2) is similar to bacterial chitinases but lacks chitinase activity. CHI3L2 protein is secreted and is involved in cartilage biogenesis. CHI3L2 is a lectin, which binds chitooligosaccharides and other glycans with high affinity, but not heparin.

Cystathionine gamma-lyase or cystathionase (CTH) is a member of the trans-sulfuration enzymes family. CTH is an enzyme which breaks down cystathionine into cysteine and alpha-ketobutyrate. The CTH catalyzes the last step in the transsulfuration pathway from methionine to cysteine. Glutathione synthesis in the liver is dependent upon the availability of cysteine. Mutations in the CTH gene cause cystathioninuria.

Fructosamine 3 Kinase (FN3K) catalyzes the phosphorylation of fructosamines which may result in deglycation, the non-enzymatic reaction of glucose with primary amines followed by Amadori re-arrangement. Phosphorylation of fructosamines instigates metabolism of the modified amine and brings about the de-glycation of fructoselysine and of glycated proteins. A high concentration of glucose may affect non-enzymatic oxidation of proteins by reaction of glucose and lysine residues (glycation). Fructosamines, the proteins altered in this way, are less active or functional.

COAA is a member of the prokaryotic pantothenate kinase family and it is the first enzyme in the Coenzyme A biosynthetic pathway. COAA phosphorylates pantothenate (vitamin B5) to form 4'-phosphopantothenate. The key factor controlling the intracellular CoA concentration is the regulation of COAA activity by feedback inhibition.

HBsAg is the surface antigenof the Hepatitis-B-Virus (HBV). The capsidof a virus has different surface proteins from the rest of the virus. The antigen is a protein that binds specifically on one of these surface proteins. It is commonly referred to as the Australian Antigen.

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.

STE20-Related Kinase Adaptor Alpha (STRADA) is a part of the STE- 20 like kinase family which stimulates MAPK pathways by activating MAPKKK. STRADA is an upstream activator of LKB1 and also leads the sub-cellular localization of LKB1 by fixing it in the cytoplasm. The interaction between STRADA-LKB1 leads to phosphorylation of STRADA and enhanced autophosphorylation of LKB1.

Trypsin (EC3.4.21.4) is part of the serine protease family. Trypsin cleaves lysine and arginine at the C-terminal side of the peptide. The hydrolysis rate is slower if an acidic residue is on either sides of the cleavage site and no cleavage occurs if a proline residue is on the carboxyl side of the cleavage site. Trypsin optimum pH is pH-7 to 9. Trypsin will also hydrolyze ester and amide linkages of synthetic derivatives of amino acids such as: benzoyl L-arginine ethyl ester (BAEE), p-toluenesulfonyl- L-arginine methyl ester (TAME), tosyl-L-arginine methyl ester, N-α-benzoyl-L-arginine p-nitroanilide (BAPNA), L-lysyl-p-nitroanilide, and benzoyl-L-tyrosine ethyl ester (BTEE). Serine protease inhibitors that inhibit recombinant trypsin include TLCK (N-p-tosyl-L-lysine chloromethyl ketone), PMSF (phenylmethanesulfonyl fluoride), benzamidine, soybean trypsin inhibitor, and ovomucoid.

tRNA 2'-phosphotransferase 1 (TRPT1) is a member of the KptA/TPT1 family. TRPT1 catalyzes the last step of tRNA splicing, the transfer of the splice junction 2'-phosphate from ligated tRNA to NAD to produce ADP-ribose 1''-2'' cyclic phosphate. TRPT1 is broadly expressed; it is weakly or not expressed in the lung, spleen, small intestine and peripheral blood leukocytes.

MSRB2 is a member of the methionine sulfoxide reductases(MSRs) family which are antioxidant repair enzymes. MSRB2 protein catalyzes the decrease of free and protein-bound methionine sulfoxide to methionine. MSRB2 has a part in protecting against oxidative stress in numerous organs.