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Paraoxonase 1 also called Esterase-A is involved in the detoxification of organophosphate insecticides such as parathion. Paraoxonase 1 may also confer protection against coronary artery disease by destroying proinflammatory oxidized lipids present in oxidized low-density lipoproteins (LDLs).

Paraoxonase-1 or PON1 is part of the paraoxonase group of proteins. PON1 is an enzyme, responsible to the toxic metabolites of a different of organophosphorus insecticides hydrolyzation. Furthermore, PON1 is a dominant anti-atherosclerotic part of HDL. The enzyme needs PPAR-gamma for activation, leading to synthesis and release of paraoxonase 1 from the liver tissue, resulting in atherosclerosis reduction. PON1 has many qualities for atheroprotective through inflammatory lipid peroxides metabolism. This enzyme can hydrolyze a large number of substrates, for example cyclic carbonates, lactones, nerve gases etc.

Paraoxonase 2 (PON2) is a member of a multigene family whose genes share 65% identity at the amino acid level, and is expressed in a variety of tissues, including the pancreas. PON2 overexpression has been shown to lower the intracellular oxidative state and reduce the cells ability to oxidize LDL. PON2 is therefore implicated in the modulation of oxidative stress.

Coproporphyrinogen Oxidase (CPOX) which is localized to the internal membrane space of erythrocytes takes part in the 6th phase of heme biosynthesis. CPOX catalyzes the oxidative decarboxylation of propionic acid side chains of rings A and B of coproporphyrinogen III. Mutations in human CPOX gene forecast the clinical result of the disease, with either hepatic hereditary coproporphyria or hematological manifestations of erythropoietic harderoporphyria.

Phosphopantothenate-cysteine ligase (PPCS) catalyzes the first step in the biosynthesis of coenzyme A (CoA) from pantothenic acid (vitamin B5), which is a vital universal pathway in prokaryotes and eukaryotes. PPCS, being one of the last enzymes in this pathway, converts phosphopantothenate to phosphopantothenoylcysteine.

Glutathione peroxidase 3 (GPX3) is a member of the glutathione peroxidase family, which acts in the detoxification of hydrogen peroxide. GPX3 shields cells and enzymes from oxidative damage, by catalyzing the reduction of hydrogen peroxide, lipid peroxides and organic hydroperoxide, by glutathione. The GPX3 protein is one of only a few 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.

PGLS is an enzyme in the second step pentose phosphate pathway. 6-Phosphogluconolactonase is crucial for the synthesis of nucleotide sugars and NADPH, the key cause for decreasing power. PGLS transforms 6-phosphogluconolactone to 6-phosphogluconate.

Pyridoxine-5'-phosphate oxidase (PNPO) is the rate-limiting enzyme in vitamin B6 synthesis. Vitamin B6 (Pyridoxal 5-prime-phosphate or PLP) is vital for normal cellular function, and some cancer cells have notable differences in vitamin B6 metabolism compared to their normal counterparts.Vitamin B6 is an essential co-factor for enzymes involved in both homocysteine metabolism and synthesis of neurotransmitters such as catecholamine. Mutations in the PNPO gene result in PNPO deficiency, a form of neonatal epileptic encephalopathy.

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.

PPCDC is a member of the HFCD (homo oligomeric flavin containing Cys decarboxylase) superfamily which takes a part in the biosynthesis of coenzyme A (CoA) from pantothenate (Vitamin B). The biosynthesis of CoA from pantothenate needs several steps: the phosphorylation of pantothenate, the conversion of 4’-hosphopantothenate to 4''-phosphopantetheine, the adenylation by phosphopantetheine adenylyltransferase to form dephospho-CoA and the phosphorylation by dephospho-CoA kinase to form CoA. PPCDC is a key player in this pathway. PPCDC converts 4''-phosphopantothenate into 4''-phosphopantetheine.

Pyridoxine-5'-phosphate oxidase (PNPO) is the rate-limiting enzyme in vitamin B6 synthesis. Vitamin B6 (Pyridoxal 5-prime-phosphate or PLP) is vital for normal cellular function, and some cancer cells have notable differences in vitamin B6 metabolism compared to their normal counterparts.Vitamin B6 is an essential co-factor for enzymes involved in both homocysteine metabolism and synthesis of neurotransmitters such as catecholamine. Mutations in the PNPO gene result in PNPO deficiency, a form of neonatal epileptic encephalopathy.

PLA2G7 is a secreted enzyme which catalyzes the degradation of platelet-activating factor to biologically inactive products. The PLA2G7 enzyme is produced by inflammatory cells and hydrolyzes oxidised phospholipids in LDL. In the blood, PLA2G7 goes mainly with LDL and less than 20% is coupled with HDL.
PLA2G7 is implicated in the development of atherosclerosis and is also a marker for cardiac disease. PLA2G7 might have a major physiologic effect in the presence of inflammatory bodily responses.
PLA2G7 alters the action of PAF (platelet-activating factor) by hydrolyzing the sn-2 ester bond to yield the biologically inactive lyso-PAF. PLA2G7 has specificity for substrates with a short residue at the sn-2 position. PLA2G7 is inactive against long-chain phospholipids.
PLA2G7 gene defects are the source of platelet-activating factor acetylhydrolase deficiency, which is a trait that is present in 27% of the Japanese population.

Inorganic pyrophosphatase (ppa) is a member of the Ppase family. PPA is an enzyme which catalyzes the conversion of one molecule of pyrophosphate to two phosphate ions. Since this is a highly exergonic reaction, it can therefore be coupled to unfavorable biochemical transformations in order to drive these transformations to completion. The role of the PPA enzyme is a critical one in the lipid metabolism (including lipid synthesis and degradation), calcium absorption and bone formation, DNA synthesis, as well as other biochemical transformations.

CysH (Phosphoadenosine phosphosulfate reductase) is a member of the PAPS reductase family, specifically those acting on a sulfur group of donors with a disulfide as acceptor. The 3 substrates of the CysH enzyme are adenosine 3',5'-bisphosphate, sulfite, and thioredoxin disulfide, whereas its two products are 3'-phosphoadenylyl sulfate and thioredoxin.

PPA1 is a member of the PPase family. PPA1 catalyzes the conversion of one molecule of pyrophosphate to two phosphate ions. Many biochemical pathways use the hydrolysis of PPi to two phosphate ions to make the reactions permanently irreversible. A prominent illustration of this phenomenon is the inorganic pyrophosphatase catalyzation in the hydrolysis reaction at the beginning of lipid degradation. Inorganic pyrophosphatase provides the motivation for the activation of fatty acids destined for oxidation by stimulating the rapid hydrolysis of pyrophosphate.

Phosphopantothenate-cysteine ligase (PPCS) catalyzes the first step in the biosynthesis of coenzyme A (CoA) from pantothenic acid (vitamin B5), which is a vital universal pathway in prokaryotes and eukaryotes. PPCS, being one of the last enzymes in this pathway, converts phosphopantothenate to phosphopantothenoylcysteine.

PPA2 shares great imagination with members of the inorganic pyrophosphatase (PPase) family. PPA2 is localized to the mitochondrion and owns the signature sequence necessary for the catalytic activity of PPase. PPases catalyze the hydrolysis of pyrophosphate to inorganic phosphate, which is vital for the phosphate metabolism of cells.

Prostatic Acid Phosphatase or ACPP is part of a family of proteins called histidine acid phosphatase. ACPP enhances the hydrolyzation of many phosphate monoesters and proteins that are phosphorylated. In order to function best, ACPP needs a range of range of 4-6 pH, furthermore, L(+)-tartrate inhibits ACPP’s catalyzation. This enzyme can act as a lipid phosphatase as well and can inhibit lysophosphatidic acid in seminal plasma.

PAPPA is a large zinc binding protein, which plays a role as a metalloprotease and specifically cleaves IGFBP-4 and IGFBP-5, resulting in release of bound IGF. PAPP-A regulates IGF bioactivity in various biological systems, including the human ovary and cardiovascular systems. PAPP A levels were higher in patients with unstable angina or acute myocardial infarction. PAPPA is also involved in local proliferative processes such as wound healing and bone remodeling. Moreover, PAPP-A is produced in high concentrations during pregnancy and is released into the maternal circulation. In placenta, PAPP A is expressed in X cells in septa and anchoring villi, and in syncytiotrophoblasts in the chorionic villi.

Phosphoserine aminotransferase (PSAT1) catalyzes the conversion of 3-phosphohydroxypyruvate into 3-phosphoserine which is dephosphorylated consequently by phosphoserine phosphatase to form L-serine. PSAT1 is probably a phosphoserine aminotransferase, based on similarity to proteins in mouse, rabbit, and Drosophila. PSAT1 is expressed at high levels in the brain, liver, kidney and pancreas, and very weakly expressed in the thymus, prostate, testis and colon. Defects in the PSAT1 gene are the cause of phosphoserine aminotransferase deficiency (PSATD). PSATD is distinguished biochemically by low plasma and cerebrospinal fluid concentrations of serine and glycine and clinically by intractable seizures, acquired microcephaly, hypertonia, and psychomotor retardation.

Bee venom phospholipase A2 (PLA) is the main allergen in the bee sting allergy. Bee venom phospholipase A2 (BV-PLA2) is a hydrolytic enzyme which specifically cleaves the sn-2 acyl bond of phospholipids at the lipid/water interface. BV-PLA2 is a 14–16-kDa glycoprotein, consisting of 134 amino acids and displaying a single carbohydrate side chain at the residue Asn13. It is also held to be responsible for some systemic anaphylactic reactions in bee venom sensitized individuals. BV-PLA2 presents 3 peptide and a glycopeptide T cell epitopes, which are recognized by both allergic and non-allergic bee venom sensitized subjects. PLA is able to elicit both IgE mediated allergy and normal immunity to bee sting which usually is associated with high affinity IgG4 anti-PLA antibodies.

P450 Oxidoreductase, also known as POR is a flavoprotein which contributes electrons to all microsomal P450 enzymes. POR is localized to the endoplasmic reticulum, where it is also capable of transfering electrons to heme oxygenase as well as cytochrome b5. POR is structurally related to two separate flavoprotein families; first one is ferredoxin nucleotide reductase and the second flavodoxin.