Alkaline phosphatase mammalian

Finally we should briefly mention the purple acid phosphatases, which, unlike the alkaline phosphatases, are able to hydrolyse phosphate esters at acid pH values. Their purple colour is associated with a Tyr to Fe(III) charge transfer band. The mammalian purple acid phosphatase is a dinuclear Fe(II)-Fe(III) enzyme, whereas the dinuclear site in kidney bean purple acid phosphatase (Figure 12.13) has a Zn(II), Fe(III) centre with bridging hydroxide and Asp ligands. It is postulated that the iron centre has a terminal hydroxide ligand, whereas the zinc has an aqua ligand. We do not discuss the mechanism here, but it must be different from the alkaline phosphatase because the reaction proceeds with inversion of configuration at phosphorus. 

Inhibits serine proteases such as trypsin and chymotrypsin. Also inhibits cysteine proteases (reversible by reduced thiols) and mammalian acetylcholinesterase Inhibits ATPase, alkaline phosphatase and tyrosine phosphatase Reagent for maintaining -SH groups in the reduced state. Effective for reducing protein disulfide bonds prior to SDS-PAGE... 

The alkaline phosphatase of E. coli is a dimer of 449-residue subunits which requires Zn2+, is allo-sterically activated by Mg2+, and has a pH optimum above 8.667/708 711 At a pH of 4, incubation of the enzyme with inorganic phosphate leads to formation of a phosphoenzyme. Using 32P-labeled phosphate, it was established that the phosphate becomes attached in ester linkages to serine 102. The same active site sequence Asp-Ser-Ala is found in mammalian alkaline phosphatases. These results, as well as the stereochemical arguments given in Section 2, suggest a double-displacement mechanism of Eq. 12-38 ... 

The amino acid sequence around the serine that is phosphorylated in the presence of inorganic phosphate at low pH can be seen in Table III (55-57). The sequence of Schwartz et al. (55) accounted for 56% of the peptides that contained 32P (20% or more of the peptides were excluded as extreme fractions when the peaks were pooled). The sequence, as far as it is known, is the same for alkaline phosphatase from a mammalian source (58). It is interesting to note, as pointed out by Boyer and others (59-64), that many hydrolytic enzymes with a serine residue at their active site have the same general sequence, i.e., Asp (Glu)-Ser-Ala (Gly). 

Agren 112) and Engstrom 113) isolated serine phosphate from mammalian alkaline phosphatase that had been incubated with inorganic phosphate in acid pH (<6). Engstrom 114) and Schwartz and Lipmann 35) later obtained similar results with E. coli alkaline phosphatase. They found that a large percentage of the enzyme is phosphorylated, that compounds like glucose 6-phosphate and sodium arsenate inhibit... 

The earliest literature references to (alkaline) phosphatases established that extracts from many mammalian tissues, particularly kidney and in-... 

B. Lorenz and H. C. Schroder (2001). Mammalian intestinal alkaline phosphatase acts as highly active exopolyphosphatase. Biochim. Biophys. Acta, 1547, 254-261. 

Redesign of Mg /Zn specificity. Mammalian alkaline phosphatase (AP) contains a tetrahedral 7xfi site see Zinc Enzymes), whereas E. coli AP has an octahedral Mg° at the corresponding location. Mntation of a single amino acid (D153H) inii. coli AP, converted the specificity and geometry of the site to that of mammalian AP. ... 

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