Phosphomonoesterase, prostatic

Acid phosphatase (acid phosphomonoesterase, EC 3.1.3.2) also catalyzes the hydrolysis of phosphoric acid monoesters but with an acidic pH optimum. It has broad specificity and catalyzes transphosphorylations. Acid phosphatases are a quite heterogeneous group with monomeric, dimeric, larger glycoprotein, and membrane-bound forms. Acid phosphatase activity is present in the heart, liver, bone, prostate, and seminal fluid. Prostate carcinomas produce large quantities of acid phosphatase, and the enzyme is, therefore, used as a biomarker [141]. 

Ostrowski, W., Wasyl, Z., Weber, M., Guminska, M., and Luchter, E., The role of neuraminic acid in the heterogeneity of acid phosphomonoesterase from the human prostate gland. Biochim. Biophys. Acta 221, 297-306 (1970). 

T3. Tsuboi, K. K., and Hudson, P. B., Acid phosphatase. III. Specific kinetic properties of highly purihed human prostatic phosphomonoesterase. Arch. Biochem. Biophys. 55, 191-205 (1955). 

The phosphomonoesterases that proved most useful in this work, although free of proteolytic impurities, were found to be complex in their behavior toward phosphate esters. As indicated in Table II, if tested with the aid of low molecular weight substrates, the intestinal (85) and the potato phosphatase (34) act on 0—P and N—P bonds, whereas the prostate enzyme (86) hydrolyzes only 0—P linkages. After the discovery of the specificity of two of these enzymes for low molecular weight N—P esters, it was noticed that the intestinal enzyme, although classified in the literature as alkaline phosphatase, hydrolyzes N—P bonds both at pH 5.6 and 9.0, but not at pH 7.0. Since the pH range of 5 to 6 is that of maximum stability of almost all proteins, most experiments were carried out in this pH range. Thus the use of these three enzymes, either alone or in combination with each other, proved to be quite a powerful tool. 

Structure of Coemyme A. The elucidation of the structure of CoA depended heavily on d radation by specific enzymes. The phosphate on carbon 3 of the adenosine was shown to be a monoester phosphate by hydrolysis with prostate phosphomonoesterase. The localization of the monoester at the 3 position was established by its sensitivity to a b nucleotidase that attacks only nucleoside 3 -pbosphates, not 2 - or 5 -phosphates. The original CoA molecule or the phosphatase product, depbospho CoA, can be split by nucleotide pyrophosphatases from potato or snake venom. These reactions permitted the identification of the adenosine phosphate portion of the molecule. The position of the phosphate on pantothenic acid cannot be determined enzymatically, but was established by studies on the synthesis of CoA from synthetic phos-phorylated pantetheines. Pantetheine is split to thiolethanolamine and pantothenic acid by an enzyme found in liver and kidney. This enzyme also attacks larger molecules, including CoA. 

Phosphomonoesterases. Enzymes with this specificity are widely distributed. They are simply called phosphatases we usually distinguish acid phosphatases with a pH optimum of about 5 and alkaline phosphatases with a pH optimum around 7 to 8. They split monoesters exclusively, the 3 -monophosphates as well as the 5 -monophosphates. One acid phosphatase occurs in remarkably high concentration in the human prostate gland. The enzyme active at the higher pH is found in the small intestine and in bones where it participates in the formation of bone tissue. 

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