Orthophosphoric monoester

Alkaline phosphatases [AP, orthophosphoric-monoester phosphorylase (alkaline optimum) EC 3.1.3.1] represent a large family of almost ubiquitous isoenzymes found in organisms from bacteria to animals. In mammals, there are two forms of AP, one form present in a variety of tissues and another form found only in the intestines. They share common attributes in that the phosphatase activity is optimal at pH 8-10, is activated by the presence of divalent cations, and is inhibited by cysteine, cyanides, arsenate, various metal chelators, and phosphate ions. Most conjugates created with AP utilize the form isolated from calf intestine. 

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. 

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) ... 

Orthophosphoric-monoester phosphohydrolase (alkaline optimuni) v - Alkaline phosphatase ALP... 

APases (orthophosphoric monoester phosphohydrolase, alkaline optimum, EC 3.1.3.1) are found primarily in animal tissues and microorganisms. APases used in EIA are isolated from bovine intestinal mucosa or from E. coli. These enzymes have considerable differences in their properties and should not, as often done, be assayed under identical conditions. 

Alkaline phosphatase (AP orthophosphoric monoester phospho-hydrolase, EC 3.1.3.1) isozymes are present in a wide range of species from bacteria to man and are capable of dephosphorylation and transphosphorylation of a broad spectrum of substrates in vitro [1]. Their broad snbstrate specificity and localization on the outside leaf of the cytoplasmic membrane suggests potential involvement in numerons extracellular processes. In humans, four isozymes of APs have been identified. One of them, tissue-nonspecific alkaline phosphatase (TNAP), is ubiquitously expressed, demonstrating especially high level of expression in bone, liver and kidney tissues. Three other isozymes demonstrate tissue-specific... 

Alkaline phosphomonoesterase. Phosphomonoesterase. An orthophosphoric monoester + H(2)0 an alcohol + phosphate. 

Tietz NW, Rinker AD, and Shaw (1983) IFCC methods for the measurements of catalytic concentrations of enzymes. Part 5. IFCC method for alkaline phosphatase (orthophosphoric monoester phosphohyfrolase, alkaline optimum, EC 3.1.3.1). Clinica Chimica Acta 135 339F-367F. 

The different varieties of orthophosphoric monoesters and diesters which are present in all living species are exceedingly numerous. Biologically important monoesters include the mononucleotides such as, for example, adenylic acid (adenosine monophosphate, AMP), inosinic acid, vitamin Bg and many phosphorylated proteins, for example, milk caseins. Biologically important diesters include the phospholipids (e.g. lecithin and phosphatidyl inositol), plasmalogens, sphingomyelins, cyclic nucleotide monophosphates (e.g. cyclic AMP), some teichoic acids, vitamin Bj2 and of course the immensely important nucleic acids (polynucleotides) (Chapters 10 and 11). The great stability of diesters is an essential feature of the chemistry of polynucleotides. 

Alkaline phosphatase, a dimeric glycoprotein that catalyses the hydrolysis of orthophosphoric monoesters, is a membrane-bound enzyme comprising four isoenzymes encoded by different structural genes tissue non-specific, intestinal, placental and germ-cell (Moss 1992). 

Poly(l,4-j8-D-mannuronide) lyase Orthophosphoric-monoester phosphohydrolase (alkaline optimum)... 

I) Phosphomonocsterases. It is well known that both acid and alkaline phospho-monoesterases (orthophosphoric monoester phosphohydrolase EC 3.1.3.1 and EC 3.1.3.2) are widely distributed in nature. These enzymes are able to split glycerophosphate formed by the action of GPC diesterase (Reaction 39) into glycerol and orthophosphate ... 

Acid phosphatases (Aps) are enzymes with a low pH that catalyze the hydrolysis of orthophosphoric monoester to alcohol and H3PO4. This enzyme has been utilized to a limited extent for the detection of pesticides through inhibition of the enzyme. AP was used with another enzyme, glucose oxidase (GOD), in abi-enzymatic biosensor for the determination of malathion, methyl parathion, and paraoxon. Biocatalytic hydrolysis of glucose-6-phosphate in the presence of acid phosphatase was reversibly... 

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