Mammals alkaline phosphatase

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. 

Phosphates of pharmaceutical interest are often monoesters (Sect. 9.3), and the enzymes that are able to hydrolyze them include alkaline and acid phosphatases. Alkaline phosphatase (alkaline phosphomonoesterase, EC 3.1.3.1) is a nonspecific esterase of phosphoric monoesters with an optimal pH for catalysis of ca. 8 [140], In the presence of a phosphate acceptor such as 2-aminoethanol, the enzyme also catalyzes a transphosphorylation reaction involving transfer of the phosphoryl group to the alcohol. Alkaline phosphatase is bound extracellularly to membranes and is widely distributed, in particular in the pancreas, liver, bile, placenta, and osteoplasts. Its specific functions in mammals remain poorly understood, but it seems to play an important role in modulation by osteoplasts of bone mineralization. 

Metabolism of pyridoxine-related compounds in mammals. Enzymes 1, pyridoxal kinase (present in all mammalian tissues) 2, nonspecific (probably alkaline) phosphatases 3, pyridoxine oxidase (cofactor is FMN O2 is required subject to product inhibition) 4, aldehyde oxidase or aldehyde dehydrogenase 5, aminotransferase,... 

An enzyme which splits a-glycerophosphate at a pH of about 5.0 has also been studied, although not as extensively as alkaline phosphatase. It has been found that this enzyme is present in cytoplasmic granules in fibroblasts of a variety of mammals. The enzyme is widely distributed in the nervous system. Shimizu found the reaction most intense in the axone... 

The following three characteristic mammalian liver and kidney enzymes are absent from muscle catalase, xanthine oxidase, and D-amino oxidase. The distribution of many other enzymes in mammals is limited to particular organs. Thus arginase occurs only in the liver, alkaline phosphatase in the intestinal mucosa, acid phosphatase in kidney, spleen, and prostate, 5-nucleotidase in the testis, and a-mannosidase in the epididymis (see Table 4.6). The blood is disproportionately rich in carbonic anhydrase, and the pancreas in ribonuclease. Glutamine synthetase, which condenses... 

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