Orthophosphate phosphatase

Acid Phosphatase Orthophosphate monoester + H20 —> an alcohol + orthophosphate. 

In contrast to tyrosine kinases, Tyrosine phosphatases (PTPs) are enzymes which act on phosphorylated proteins and catalyze the transfer of a phosphate group from a tyrosine residue to a water molecule, generating orthophosphates in a process which is referred to as dephosphorylation. PTPs are involved in many cellular signal transduction pathways. 

Condensed (poly) phosphates may exert different effects on calcium utilization than the aforementioned effects of simple (ortho-) phosphates. Polyphosphates have a much greater affinity for calcium than do orthophosphates, and soluble calcium-polyphosphate complexes are readily formed in the gastric and intestinal environments. In addition, polyphosphates must be hydrolyzed by an intestinal alkaline phosphatase (27) prior to absorption. We have found polyphosphates to be incompletely (80.5%) hydrolyzed to orthophosphate during the digestive process in young adult males when calcium intake was low only 56% of a 1 g phosphorus supplement was absorbed from a polyphosphate sources as compared to 71% from an orthophosphate source (5). 

Purple acid phosphatases (PAPs) occur widely in nature and are responsible for hydrolysis of orthophosphate monoethers to alcohols under acidic conditions according to the reaction... 

This enzyme [EC 3.1.3.1], also known as alkaline phos-phomonoesterase, phosphomonoesterase, and glycero-phosphatase, catalyzes the hydrolysis of many ortho-phosphoric monoesters (the substrate specificity is quite wide) to generate an alcohol and orthophosphate. The... 

Because alkaline phosphatase converts ATP or GTP to their respective nucleosides, use of alkaline phosphatase to deplete ATP or GTP should be reserved for those cases where this does not present a problem Furthermore, alkaline phosphatase is potently inhibited by orthophosphate so higher than would be anticipated amounts of enzyme are required for efficiently depleting ATP or GTP. 

This enzyme [EC 3.1.3.9] catalyzes the hydrolysis of o-glucose 6-phosphate to yield o-glucose and orthophosphate. Some glucose phosphatases also catalyze transphosphorylation reactions from carbamoyl phosphate, hexose phosphates, pyrophosphate, phosphoenolpyru-vate and nucleoside di- and triphosphates, using D-glu-cose, D-mannose, 3-methyl-D-glucose, or 2-deoxy-D-glu-cose as phosphoryl acceptors. See Isotope Exchange (Reactions Away from Equilibrium)... 

Also known as inositol-1,4-bisphosphate 1-phosphatase [EC 3.1.3.57], this enzyme catalyzes the hydrolysis of d-myo-inositol 1,4-bisphosphate to generate D-myo-inositol 4-phosphate and orthophosphate. This enzyme can also act on inositol 1,3,4-trisphosphate (forming inositol 3,4-bisphosphate). Inositol-1,4,5-trisphosphate 1-phos-... 

Inositol-1,4,5-trisphosphate 5-phosphatase [EC 3.1.3.56], also known as inositol trisphosphate phosphomonoester-ase and inositol polyphosphate 5-phosphatase, catalyzes the hydrolysis of D-myo-inositol 1,4,5-trisphosphate to produce D-myo-inositol 1,4-bisphosphate and orthophosphate. The type I enzyme (but not the type II enzyme) will also hydrolyze inositol 1,3,4,5-tetrakisphosphate at the 5-position. However, neither of the two... 

This set of enzymes [EC 3.1.3.16], also known as serine/ threonine-specific protein phosphatases, catalyzes the hydrolysis of a seryl- or threonyl-bound phosphate group from a wide range of phosphoproteins, including a number of enzymes which have been phosphorylated under the action of a kinase. Thus, phosphoprotein J- water yields protein J- orthophosphate. 

Orthophosphate as substrate or product, ACETATE KINASE (PYROPHOSPHATE) ACETYL-CoA CARBOXYLASE ACID PHOSPHATASE ACTOMYOSIN ATPase ACYL PHOSPHATASE ASPARTATE-SEMIALDEHYDE DEHYDROGENASE ATPases... 

Horiuchi et al. (2), and Torriani (S) that orthophosphate repressed the formation of a nonspecific phosphomonoesterase in E. coli that research on this enzyme began. This work (2, 3) showed a maximum rate of synthesis of the enzyme occurred only when the phosphate concentration became low enough to limit cell growth. With sufficient phosphate, the amount of active enzyme is negligible. Under conditions of limiting phosphate, alkaline phosphatase accounts for about 6% of the total protein synthesized by the cell (4). 

Although it is widely found in bacteria, the physiological function of alkaline phosphatase is still unknown. The enzyme is nonspecific (4, 28), and this would be desirable if its role were to supply phosphate from phosphate esters under conditions of phosphate deprivation. Although the enzyme is repressed by orthophosphate in many strains of E. coli, it is constitutive in most other bacteria (29), thus phosphate deprivation... 

In studies with alkaline phosphatase it has been found that the enzymic activity measured by the release of p-nitrophenol from p-nitrophenyl phosphate increases with the concentration of tris buffer much faster than it increases with the ionic strength of other salts such as NaCl and Mg2SO< (4, 50). This behavior of tris was shown by Dayan and Wilson (122, 123) to result from a transphosphorylation reaction, where 0.5 M tris reacts with phosphoryl enzyme to form tris phosphate at the same rate as does 55 M water to form orthophosphate. 

Acid phosphatase or orthophosphoric monoester phosphohydrolase (EC 3.1 3.2) activity is widespread throughout nature. Hydrolysis of a variety of orthophosphate esters as well as transphosphorylation reactions are catalyzed by enzymes from many sources. Table I illustrates their ubiquitous nature. 

Phosphatase Hydrolysis of phosphate Translocation of ATPases linked to cation Inorganic pyrophosphatase (pyrophosphate orthophosphate + P043-) Glucose-6-phosphatase Fructose-1,6-bisphosphatase Alkaline phosphatase Phosphoprotein phosphatase (Na+, K+)-ATPase (Mg2+, Ca2+)-ATPase Proton-translocating ATPase Zn2+ Zn2+ Sodium pump Calcium pump H+ pump... 

Alkaline phosphatases form a widespread group of relatively unspecific enzymes catalyzing the hydrolysis of many orthophosphate monoesters. Their pH optima are generally at pH 8 or above. Several alkaline phosphatases have been shown to contain zinc (3). 

The mode of action of vanadyl(IV) ion in mimicking insulin is not clearly defined. It has been speculated that V02+.may be inhibiting cellular phosphatases33. Since alkaline phosphatase is strongly inhibited by V02+ 68, the metal may have a functional role in regulating phosphatase activity in cells. In a very recent development, insulin has been found to stimulate phosphorylation with orthophosphate of the 95,000 molecular weight... 

Identification of N-, P-, and S-containing compounds is difficult, and those that are identified tend to be metabolic products, such as nucleotides and vitamins, released into the soil following the death of cells. Broadly, nitrogen is an integral part of the humic molecule, and is released as NH4 ions when the humic material is degraded. Phosphorus and sulfur are more commonly found as P and S esters, which can be released as orthophosphate and sulfate ions by the action of phosphatase and sulfatase enzymes, respectively. 

Further study of this synthesis in partly purified extracts did not reveal any requirements for cofactor or metal. Shikimate 5-phosphate (alone) was extensively hydrolyzed in these extracts to shikimate and orthophosphate, but, when equimolar amounts of enolpyruvate phosphate were also added, only insignificant quantities of shikimate were produced, and, for every mole of Zl formed, two equivalents of orthophosphate were released. The phosphatase action on shikimate 5-phosphate was strongly inhibited when the amount of enolpyruvate phosphate present was equivalent to only 10 per cent of the shikimate 5-phosphate, but Zl added initially to shikimate 5-phosphate did not inhibit the phosphatase activity. 

N3. Nigam, V. N., Davidson, H. M., and Fishman, W. H., Kinetics of hydrol5rsis of the orthophosphate monoesteis of phenol, p-nitrophenol and glycerol by human prostatic acid phosphatase. J. Biol. Chem. 234, 1550-1554 (1959). 

Alkaline phosphatase (E.C.3.1.3.1) is also used in many enzyme-amplified immunoassays. It catalyzes the hydrolysis of an orthophosphoric monoester, to produce an alcohol and orthophosphate. This 100 kDa enzyme has a pH optimum near 9, and exhibits activities of 1000 U/mg (37 °C). With p-nitropheny I phosphate as substrate, the p-nitrophenol produced may be monitored at 450 nm (Eq. 6.11) ... 

Francko and Heath (1979) studied the influence of UV radiation on the phosphate complexation properties of dissolved humic substances from Crazy Eddie Bog in the central United States. In this bog, filterable phosphorus compounds were largely associated with humic substances of high apparent molecular weight. These fulvic acid-phosphorus associations resisted hydrolysis by alkaline phosphatase, but released orthophosphate upon irradiation with low doses of UV radiation, " e turnover time of the fulvic acid-phosphorus compounds was calculated to be less than 1 hour at the surface of a lake on a cloudless day. 

Phosphatase calcium phosphate culture medium phenyldisodium orthophosphate... 

The third most important nutrient phosphorous is taken up from the environment as orthophosphate. Phosphorous are generally strongly bound to compounds in the environment. It can be as phosphate containing organics or as insoluble salts in the soil or present as minerals in rocks. Fungi use extracellular phosphatases to liberate phosphorous from organics. They also produce organic acids to dissolve insoluble salts and rocks to be able to take up phosphorous. 

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