Acid phosphatase general

Even more interesting is the observed regioselectivity of 37 its reaction with 2, 3 -cCMP and 2, 3 -cUMP resulted in formation of more than 90% of 2 -phosphate (3 -OH) isomer. The postulated mechanisms for 37 consists of a double Lewis-acid activation, while the metal-bound hydroxide and water act as nucleophilic catalyst and general acid, respectively (see 39). The substrate-ligand interaction probably favors only one of the depicted substrate orientations, which may be responsible for the observed regioselectivity. Complex 38 may operate in a similar way but with single Lewis-acid activation, which would explain the lower bimetallic cooperativity and the lack of regioselectivity. Both proposed mechanisms show similarities to that of the native phospho-monoesterases (37 protein phosphatase 1 and fructose 1,6-diphosphatase, 38 purple acid phosphatase). 

Surprisingly, too, there are claims of higher oxidation states of Mn in some systems, e.g. Mnlv in photosynthetic(II) chloroplast systems and Mn111 in acid phosphatase. In the latter enzyme Tyr and Cys residues appear to form part of the metal-binding site. The metal is also involved in the phosphate binding. While superoxide dismutase (SOD) is more generally found with Cu and Zn as the active metals, an Mn-SOD form is found in certain bacteria. The Mn oscillates between different oxidation states in its catalytic activity.149... 

Beckman et al. (28) have studied the electrophoretic separation of the acid phosphatase activity in tissue extracts on starch gel at pH 8. They described four electrophoretic bands A, B, C, and D. Table IV (28) shows the distribution of activity in different organ extracts. The ABD pattern predominated in kidney BD in liver, intestine, heart, and skeletal muscle B in skin and D in pancreas. The C component was present in a large number of placentae but not in other adult organs. All four electrophoretic components were inhibited by d-(- -)-tartrate A contained sialic acid, D had a lower pH optimum and was more heat resistant than A, B, and C. Components C and D showed parallel electrophoretic behavior. In human skin fibroblasts grown in tissue culture, the acid phosphatase was generally high and the most common pattern was BD. Almost every culture showed some activity. The BD... 

An acid phosphatase from the mycelium of the fungus Neurospora crassa has been purified 1400-fold with a 40% recovery. The pH maximum is 5.6 with j3-glycerophosphate as substrate. Fluoride and D-(-f-)-tartrate are competitive inhibitors so that this enzyme fits into a rather general pattern for others of its type which have been described (116). 

Patni, N.J. Aaronson, S. (1974). Partial characterization of the intra-and extracellular acid phosphatase of an alga, Ochromonas dancia. Journal of General Microbiology 83, 9-20. 

Enhancement of POD-capacity and appearance of new isoforms is generally considered as an important criterion for senescence (Hazell and Murray, 1982). Lee et al. (1976a) suggested that the cadmium-induced capacity increase of POD and several hydrolytic enzymes (ribonuclease, deoxyribonuclease, acid phosphatase) in Glycine max should constitute an accelerated senescence response. In Zea mays, an induction of leaf acid phosphatase was also reported for toxic concentrations of lead (Maier, 1978 b). 

Stor e characteristics of the native enzyme are generally good, with activities maintained over years. Alkaline phosphatase conjugates are usually prepared via amino or carboxylic acid side chains and purified by gel filtration chromatography. Conjugates are very stable, but the enzyme is costly due to the limited supply of calf intestine. Alkaline (and also neutral and acid) phosphatase enzymes in biological samples are a potential problem with the use of this enzyme label. Careful washing of solid phases may be required to ensure no interference in assays. 

The dephosphorylation of 5-chloro and 5-bromo-D-xylulose-l-phosphate was carried out by the addition of acid phosphatase. After purification, 5-chloro-D-xylu-lose and 5-bromo-D-xylulose were recovered as pure compounds in 47 and 12% yields, respectively, from DHAP. In this study, we have shown that DHAP generated from glycidol 7 can be used in situ as a donor substrate of FruA in the presence of 2-halo-acetaldehydes 20 as acceptor substrates for the synthesis of 5-halo-D-xylulose 19. Given that DHAP aldolases display a broad specificity towards acceptor substrates, this strategy can be applied generally to the synthesis of various analogs of monosaccharides. 

In general there are three phosphatase families alkaline, acid, and protein phosphatases. Alkaline phosphatases are typically dimers that contain three metal ions per subunit and have a pH optimum pH above 8. Acid phosphatases exhibit an optimum pH<7 and are usually divided into three classes low molecular weight acid phosphatases (<20 kDa), high molecular weight acid phosphatases (50-60 kDa), and purple acid phosphatases (which contain an Fe-Fe or Fe-Zn center at the active site). Phosphatases specific for I-l-P appear to be most similar (in kinetic characteristics but not in mechanism) to the alkaline phosphatases, but their structures define a superfamily that also includes inositol polyphosphate 1-phosphatase, fructose 1, 6-bisphosphatase, and Hal2. The members of this superfamily share a common structural core of 5 a-helices and 11 (3-strands. Many are Li+-sensitive (York et al., 1995), and more recent structures of archaeal IMPase proteins suggest the Li+ -sensitivity is related to the disposition of a flexible loop near the active site (Stieglitz et al., 2002). 

CoA undergoes dephosphorylation, catalyzed by lysosomal acid phosphatase, to dephospho-CoA, followed by pyrophosphatase action to release 4 -phosphopantetheine and 5 -AMP - the reverse of the final stages of CoA synthesis shown in Figure 12.2. CoA is also a substrate for direct pyrophosphatase action, at about 10% of the rate of action on dephospho-CoA. The pyrophosphatase seems to be a general nucleotide pyrophosphatase of plasma membrane rather than an enzyme specific for the degradation of CoA. 

The reader is referred to the following sources of further information on the specific cocatalytic enzymes superoxide dismutase, and the reduced form, alkahne phosphatases, nuclease Pl, purple acid phosphatase, amidohydrolase, leucine amtnopeptidase, general comments on the mechanisms of the phosphatases and aminopeptidases, and other cocatalytic zinc enzymes. ... 

These results were confirmed to a large extent by Lundin and Allison (L14, L15), who examined the electrophoretic patterns of acid phosphatase from different organs and animal forms. We shall concern ourselves only with the results on human tissues. Since there is no statement that equal activities of acid phosphatase from different tissues were placed at the origin, it is difBcult to make any definite conclusions about the patterns from the different tissues. In general, these tissues showed between 10 and 17 bands upon electrophoresis at pH 6.0 for a period of about 4 hours. Human prostate had a strong band that moved very little from the origin, and this band was not seen in the other tissues. 

Using electron microscopy, Novikoff et al. (N6) found that rat liver fractions rich in these lysosomal enzymes, particularly acid phosphatase, showed the presence of mitochondria but had a predominance of single-membrane-limited bodies which were generally electron dense. Fractions with a low acid phosphatase activity rarely showed dense bodies. This observation provided some correlation between the biochemical concept of lysosomes and the existence of a structural unit within the cell (S28). 

Two distinct peaks of acid phosphatase activity were detected in each phenotype, but the positions of these peaks differed. For example, in phenotype A, the peaks were approximately at tubes 150 and 190 in B, at about 130, 170, and 265 in BA, at 110 and 155. In these three, the first peaks showed minor enzyme activity. In CA, there was a major peak at about tube 130 and a smaller one at about tube 170. The shape of the curves varied according to the phenotype tested. In general, these results confirmed what gel electrophoresis originally showed, namely, that there are charge differences between the various isoenzymes. The electrophoretic patterns may also be influenced by the type of buffer used to make up the starch gel (K2). 

In addition to the studies cited above, there are several others showing that phenyl phosphate is much more readily hydrolyzed than j3-glycerophosphate by acid phosphatase from human erythrocytes, whereas no such marked difference exists with respect to human prostatic phosphatase (B2, Tl, T3). Unfortunately, there do not appear to be any systematic investigations of the substrate-velocity relationship for the acid phosphatases of other human tissues. In general, the available data would indicate that /3-glycerophosphate is a more specific substrate than phenyl phosphate for the detection and assay of acid phosphatase coming from the prostate. 

The injection of estrogen had a similar effect. For example, one patient was injected with 30 mg of stilbestrol in 23 days. The serum acid phosphatase decreased from 48 to 4.5 K.A. units and remained at the latter level for another 10 days of observation. In general, the decreases were not as marked as those reported for patients who had been orchiectomized. 

One female and one male patient had hyperparathyroidism with elevated serum alkaline phosphatase activities and extensive bone changes characteristic of generalized osteitis fibrosa cystica. In both instances, the serum acid phosphatase activity of the serum fell to normal values after removal of the parathyroid adenoma despite transitorily increased serum alkaline phosphatase activity. The fifth patient was a female with osteopetrosis involving the major part of the skeleton. The serum acid phosphatase was 8.7 K.A. units, the highest in the control series— yet the serum alkaline phosphatase was within normal limits. It would appear, therefore, that some patients with skeletal disease may have a slight but definitely elevated serum acid phosphatase activity, at least as determined by the Gutman method (GIO, G14), which cannot be explained by concurrent prostatic carcinoma or by a spillover of alkaline phosphatase activity to a pH of 5.0. 

Although serum acid phosphatase activity has already been considered in certain diseases of childhood, such as leukemia or Gaucher s disease, it may be of value to make several general comments in this area. Laron and Kowadlo (L4) found that the mean normal values for total serum acid phosphatase were 5.23 1.26 K.A. units for children 1 year of age and 4.63 0.93 K.A. units for children 2-8 years of age. These are higher than the values for adults. The mean value for l- (-I-) -tartrate-inhibited acid phosphatase activity was 0.21 0.28 K.A. units for all age groups. 

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