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PubMed1991

Comparison of the antigenic peptides between human prostatic and lysosomal acid phosphatases.

The relative antigenicity (capacity to bind antibodies raised against the intact prostatic acid phosphatase) of the selected peptides from human prostatic and lysosomal acid phosphatases was evaluated in a competitive assay. Both prostatic and lysosomal acid phosphatases were shown to possess similar antigenic determinants on both terminal regions, along with more similarity on NH2-terminal peptide than COOH-terminal site. At least one additional antigenic site is present at the internal region of prostatic acid phosphatase, since the mixture of both amino- and carboxyl-terminal peptides exhibited only 70% inhibition.

Acid Phosphatase↗
PubMed1978

Immunochemical detection of serum prostatic acid phosphatase. Methodology and clinical evaluation.

An immunochemical method for detection of prostatic acid prosphatase is described. Purified acid phosphatase was isolated from cancerous human prostate. A specific antiserum to the purified enzyme was produced in rabbits. The antiserum to postatic acid phosphatase did not react with acid phosphatase originating from other tissues. A counter immunolectrophoresis, utilizing the specific antibodies and a chemical staining technique, has been developed and clinically evaluated. Sera from patients with prostatic carcinoma (6/20 of stage B, 27/49 of stage C, and 98/125 of stage D) gave positive results. Sera from 19 patients with benign prostatic hypertrophy, from 89 patients with other tumors, from 12 patients with Gaucher's disease, from 107 healthy volunteers, and from 50 normal age-matched men all gave negative results. The sensitivity of this method was 0.4 IU of enzyme activity or 20 ng per ml of prostatic acid phosphatase protein. Further clinical evaluation of patients in the early stage of prostatic cancer and of patients undergoing chemotherapy is in progress.

Acid Phosphatase↗
PubMed1987

Antibodies to porcine uteroferrin used in measurement of human tartrate-resistant acid phosphatase.

The immunological similarity between human tartrate-resistant acid phosphatase (EC 3.1.3.2) and porcine uteroferrin previously reported for the isoenzyme from spleens of patients with leukemic reticuloendotheliosis (Ketcham et al., J Biol Chem 1985;260:5768-76) has been confirmed for partly purified acid phosphatase found in the spleen of a patient with Gaucher's disease, and for the corresponding isoenzyme in other tissues and serum. Anti-uteroferrin antibodies raised in rabbits have been used to demonstrate the feasibility of their application in an immunoassay for tartrate-resistant acid phosphatase in serum.

Acid Phosphatase↗
PubMed1989

Acid phosphatase (EC 3.1.3.2) synthesis by phosphorus regulatory mutant strains of Neurospora crassa.

1. Even though altered forms of acid phosphatase II were synthesized by the mutant strains nuc-1A and nuc-2A of N. crassa, their synthesis was independent of exogenous phosphate concentrations. 2. Synthesis of acid phosphatase I by nuc-2A was also insensitive to exogenous phosphate concentrations. When nuc-1A was grown on a low-phosphate medium, it also produced a heat-labile acid phosphatase in addition to a I-like acid phosphatase. I-like acid phosphatase was not detected in the mycelium of the pregc mutant strain grown on low-phosphate medium. 3. These results are consistent with the participation of the nuc-2, preg and nuc-1 genes in regulating the transport and/or secretion of acid phosphatase and probably other phosphatases by Neurospora crassa.

Acid Phosphatase↗
PubMed1985

A prostatic-like acid phosphatase is present in human lactating milk.

The presence of a prostatic-like acid phosphatase is reported in human lactating milk. Its activity is associated with skim milk and it could be separated from the other acid phosphatases only after Triton X-100 treatment. By all the criteria applied, it appears to be very similar to prostatic acid phosphatase. An approximate molecular weight of 96 000 was measured for the native enzyme, which is inhibited by L-(+)tartrate and has similar electrophoretic migration. Besides, it hydrolyzes choline-o-phosphate very well and cross-reacts with an antibody anti-prostatic acid phosphatase. This prostatic-like acid phosphatase has also been detected in a human mammary carcinoma from a lactating patient.

Acid Phosphatase↗
PubMed1981

Ultrastructural localization of acid phosphatase activity in the small intestinal absorptive cells of postnatal rats.

The ultrastructural localization of acid phosphatase activity was investigated in ultrathin (0.05 micrometer) and semithin (0.5 micrometer) sections of the small intestinal epithelial cells of postnatal rats. Until around the 15th day of neonatal life acid phosphatase activity in the duodenal and jejunal epithelial cells was observed on the microvillous membrane, the membrane of the tubulo-vacuolar system, the lateral cell membrane, the lysosomes, the Golgi apparatus and the GERL of Novikoff (1963). After about the 15th neonatal day, the tubulo-vacuolar system enzyme disappeared form both cells. Acid phosphatase activity then became localized on the microvillous membrane, the lateral cell membrane, the lysosomes, the Golgi apparatus, and the GERL, as in adult rats. During the suckling period, acid phosphatase in the ileal cells could be seen on the microvillous membrane, the lateral cell membrane, the Golgi apparatus, the GERL, the membrane of tubulo-vacuolar system and the supranuclear vacuole. At weaning, however, the tubulo-vacuolar system and the supranuclear vacuole enzyme disappeared, and only the lysosomes and the GERL of these cells showed acid phosphatase activity, as in the adult rat. It was concluded that the acid-phosphatase-containing tubulo-vacuolar system and the supranuclear vacuole in the epithelial cells of the distal intestine of suckling rats may possess a strong phagolysosomal function as well as having an absorptive capacity.

Acid Phosphatase↗
PubMed1992

A histochemical study of acid phosphatases in medullary bone matrix and osteoclasts in laying Japanese quail.

Acid phosphatase activity in medullary bone matrix and osteoclasts of laying Japanese quail was examined histochemically. To avoid nonspecific staining, the reactivity of the enzyme was evaluated using both the azo dye method and the lead salt method and nonembedded thick sections and resin-embedded thin sections. The pH of the incubation medium was also varied from the acid range (pH 5.0 and 6.5) to the alkaline range (pH 8.5). Medullary bone osteoclasts contain both tartrate-resistant acid phosphatase (TRAP) activity and fluoride-resistant acid phosphatase (FRAP) activity, and no significant difference in intensity was detected between active and inactive osteoclasts. The entire matrix of medullary bone was positive for tartrate-resistant, fluoride-sensitive acid phosphatase activity. No reaction product was observed in sections incubated in substrate-free and pH 8.5 media. The results demonstrate the existence of FRAP in medullary bone osteoclasts and suggest that medullary bone matrix includes TRAP throughout the matrix.

Acid Phosphatase↗
PubMed2006

Isolation and biochemical characteristics of a molecular form of epididymal acid phosphatase of boar seminal plasma.

The fluid of boar epididymis is characterized by a high activity of acid phosphatase (AcP), which occurs in three molecular forms. An efficient procedure was developed for the purification of a molecular form of epididymal acid phosphatase from boar seminal plasma. We focused on the epididymal molecular form, which displayed the highest electrophoretic mobility. The purification procedure (dialysis, ion exchange chromatography, affinity chromatography and hydroxyapatite chromatography) used in this study gave more than 7000-fold purification of the enzyme with a yield of 50%. The purified enzyme was homogeneous by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The purified molecular form of the enzyme is a thermostable 50kDa glycoprotein, with a pI value of 7.1 and was highly resistant to inhibitors of acid phosphatase when p-nitrophenyl phosphate was used as the substrate. Hydrolysis of p-nitrophenyl phosphate by the purified enzyme was maximally active at pH of 4.3; however, high catalytic activity of the enzyme was within the pH range of 3.5-7.0. Kinetic analysis revealed that the purified enzyme exhibited affinity for phosphotyrosine (K(m)=2.1x10(-3)M) and was inhibited, to some extent, by sodium orthovanadate, a phosphotyrosine phosphatase inhibitor. The N-terminal amino acid sequence of boar epididymal acid phosphatase is ELRFVTLVFR, which showed 90% homology with the sequence of human, mouse or rat prostatic acid phosphatase. The purification procedure described allows the identification of the specific biochemical properties of a molecular form of epididymal acid phosphatase, which plays an important role in the boar epididymis.

Acid Phosphatase↗
PubMed1965

OBSERVATIONS ON THE ACID PHOSPHATASES OF EUGLENA GRACILIS.

When a bleached strain of Euglena is maintained in a medium containing very low con centrations of phosphate, the acid phosphatase activity increases. The increase in acid phosphatase activity is prevented by Actinomycin D and by p-fluorophenylalanine (PFA), indicating that the increased activity is due to de novo synthesis of acid phosphatase. When phosphate is replenished, the acid phosphatase activity decreases to the level characteristic of uninduced cells before there is any appreciable cell division. When cell division resumes in the presence of PFA, the level of acid phosphatase activity remains approximately constant. This indicates that there are two different phosphatases: a constitutive enzyme, whose synthesis is insensitive to the presence of PFA, and an induced enzyme, whose synthesis is sensitive to PFA. These enzymes are not equally sensitive to changes in pH and in fluoride concentration, thus permitting them to be assayed individually in whole toluene-treated cells. Induced cells also acquire the ability to remove phosphate from the medium very rapidly.

Acid Phosphatase↗
PubMed1991

An acid phosphatase as a biochemical marker for intestinal development in the nematode Caenorhabditis elegans.

We describe an acid phosphatase enzyme (EC 3.1.3.2) that is localized to the intestine of the nematode Caenorhabditis elegans and that should serve as a convenient biochemical marker for gut differentiation. In adult worms, acid phosphatase activity is located along the edge of the gut lumen in the vicinity of the intestinal brush border. All but the anterior six cells of the intestine stain for phosphatase activity; the nonstaining cells all descend from the Ea(l/r)(a/p)a cells. Acid phosphatase activity is low in oocytes and early embryos but increases substantially when embryos reach late morphogenesis stage; this increase corresponds to the appearance of a major band of acid phosphatase activity detectable on isoelectric focusing gels. We designate this band as the product of the pho-1 gene. The pattern of acid phosphatase expression in several embryonic mutants suggests that pho-1 expression in the developing intestine is lineage autonomous. We induced an isoelectric focusing variant in the pho-1 enzyme and used this to map the pho-1 locus about 1.5 map units to the left of center of chromosome II. We purified the pho-1 enzyme to homogeneity (6500-fold purification; 4% recovery of activity); the pho-1 acid phosphatase is a homodimeric glycoprotein with a subunit molecular weight of 55,000 Da. This paper establishes a new experimental system with which to investigate the molecular basis of lineage-specific gene expression during C. elegans development.

Acid Phosphatase↗
PubMed1993

Three-dimensional structure of rat acid phosphatase.

The crystal structure of recombinant rat prostatic acid phosphatase was determined to 3 A resolution with protein crystallographic methods. The enzyme subunit is built up of two domains, an alpha/beta domain consisting of a seven-stranded mixed beta-sheet with helices on both sides of the sheet and a smaller alpha domain. Two disulfide bridges between residues 129-340 and 315-319 were found. Electron density at two of the glycosylation sites for parts of the carbohydrate moieties was observed. The dimer of acid phosphatase is formed through two-fold interactions of edge strand 3 from one subunit with strand 3 from the second subunit, thus extending the beta-sheet from seven to 14 strands. Other subunit-subunit interactions involve conserved residues from loops between helices and beta-strands. The fold of the alpha/beta domain is similar to the fold observed in phosphoglycerate mutase. The active site is at the carboxy end of the parallel strands of the alpha/beta domain. There is a strong residual electron density at the phosphate binding site which probably represents a bound chloride ion. Biochemical properties and results from site-directed mutagenesis experiments of acid phosphatase are correlated to the three-dimensional structure.

Acid Phosphatase↗
PubMed1978

An essential active-site histidine residue in human prostatic acid phosphatase. Ethoxyformylation by diethyl pyrocarbonate and phosphorylation by a substrate.

Human prostatic acid phosphatase (orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2) is a dimeric (alpha 2) protein that catalyses the hydrolysis of phosphomonoesters. Several reports suggest that a phosphoenzyme intermediate is involved in the mechanism of acid phosphatase. Chemical modification studies and trapping experiments were therefore undertaken in order to ascertain the identity of the amino acid residue(s) involved in the formation of this intermediate. Human prostatic acid phosphatase is inactivated by diethyl pyrocarbonate (second-order rate constant of 7 M-1. min-1 at pH 6.2) with an accompanying increase in absorbance at 242 nm due to formation of ethoxyformylhistidyl derivatives. In the presence of competive inhibitors the rate of inactivation is decreased. Inactivation can be partially reversed by hydroxylamine. The pH curve of inactivation indicates the involvement of a residue having a pK alpha of 6.5. Direct evidence for the involvement of a histidine residue in the mechanism was obtained by trapping a covalent phosphohistidyl-enzyme intermediate. Incubation of the enzyme with p-nitrophenyl [32 P] phosphate leads to incorporation of 0.44 mol 32P/mol enzyme. The denatured phosphoenzyme,which was acid labile but base stable, was hydrolyzed in 3 M KOH and the radioactivity was found to cochromatograph with synthetic tau-phosphohistidine on Dowex-1 ion-exchange resin. These results are consistent with a catalytic mechanism involving histidine as a nucleophile in the formation of a covalents phosphoenzyme intermediate.

Acid Phosphatase↗
PubMed1982

Multiple forms of acid phosphatase in rat secretory enamel organ.

Acid phosphatase activity was studied biochemically in homogenates of secretory enamel organs from the rat. Incubations with crude homogenate failed to show distinct pH optima or kinetics characteristic for single enzymes. Crude homogenate activity was strongly inhibited by concentrations higher than 1 mM of NaF and Na-tartrate, and higher than 10 mM of ZnSO4 and para-bromotetramisole oxalate. 10 mM MgCl2 gave a slight stimulation. CaCl2, KCl and EDTA were uneffective. Electrophoretic separation of the crude homogenate acid phosphatase on Triton X-100 containing polyacrylamide gel demonstrated the presence of at least three multiple forms of the enzyme. Two of them showed distinct pH optima at pH 4.4. The third one showed a broad pH plateau in the acid pH range. Kinetic studies of the three forms indicated single enzyme reactions. Two forms had electrophoretic mobilities similar to alkaline phosphatase. One form could be solubilized only after Triton X-100 treatment. All forms were strongly sensitive to 10 mM NaF when added to the reaction mixture. The sensibility to 10 mM ZnSO4, CuSO4, Na-tartrate and para-bromotetramisole oxalate differed between the different forms.

Acid Phosphatase↗
PubMed1990

Effects of seven different mutations in the pho1 gene on enzymatic activity, glycosylation and secretion of acid phosphatase in Schizosaccharomyces pombe.

Structural gene mutants of the cell-surface glycoprotein acid phosphatase of Schizosaccharomyces pombe were analysed to define structural determinants that are responsible for enzymatic activity, N-glycosylation and secretion. All seven defined mutations cause a single amino acid substitution in the mature acid phosphatase protein and destroy the enzymatic activity. The mutational lesions are distributed throughout the pho1 gene. A ser to phe substitution at position 349 abolishes enzymatic activity only and does not affect glycosylation and secretion. Two mutations create a new N-glycosylation site by substitution of pro at position 56 by phe and ser, respectively. This new site is apparently used in the mutants. Their core-glycosylated acid phosphatase is slightly larger than that of the wild type. Overglycosylation seems not to affect secretion. Four different mutations (a gly to asp substitution at position 281 and ser to phe substitutions at positions 150, 271 and 277) cause intracellular accumulation of enzymatically inactive core-glycosylated acid phosphatase precursor. These mutational lesions apparently block transport of acid phosphatase from the endoplasmic reticulum to the Golgi apparatus.

Acid Phosphatase↗
PubMed1978

Phosphate (oxygen)-water exchange reaction catalyzed by human prostatic acid phosphatase.

Conclusive evidence is presented that an acid phosphatase catalyzes phosphate (oxygen)-water exchange. Studies conducted with human prostatic acid phosphatase by two independent methods have established that, despite earlier reports to the contrary, the enzyme catalyzes an exchange reaction between oxygen atoms of phosphate ion and of water. Kinetic data were obtained both by chemical conversion to trimethyl phosphate followed by mass spectroscopy and by a totally independent method involving 31P isotope shift nuclear magnetic resonance spectroscopy. Analysis showed that the enzyme catalyzes the exchange in a random, noncoupled process. If any coupled exchange occurs, it must represent less than 10% of the total. By mass spectral analysis, catalytic rate constants kcat = 0.14 sec-1 (4 degrees) and 1.8 sec-1 (37.5 degrees) were obtained. By 31P nuclear magnetic resonance kcat = 1.6 sec-1 (31 degrees) was obtained. The energy of activation for the exchange reaction is approximately 13kcal mol-1. The kcat value for exchange is about 10-fold greater than that observed with Escherichia coli alkaline phosphatase.

Acid Phosphatase↗
PubMed1989

In vitro studies on the translocation of acid phosphatase into the endoplasmic reticulum of the yeast Saccharomyces cerevisiae.

We demonstrate here the in vitro translocation of yeast acid phosphatase into rough endoplasmic reticulum. The precursor of the repressible acid phosphatase from Saccharomyces cerevisiae encoded by the PHO5 gene, was synthesized in a yeast lysate programmed with in vitro transcribed PHO5 mRNA. In the presence of yeast rough microsomes up to 16% of the acid phosphatase synthesized was found to be translocated into the microsomes, as judged by proteinase resistance, and fully core-glycosylated. The translocation efficiency however, decreased to 3% if yeast rough microsomes were added after synthesis of acid phosphatase had been terminated. When a wheat-germ extract was used for in vitro synthesis, the precursor of acid phosphatase was translocated into canine pancreatic rough microsomes and thereby core-glycosylated in a signal-recognition-particle-dependent manner. Replacing canine with yeast rough microsomes in the wheat-germ translation system, however, resulted in a significant decrease in the ability to translocate and glycosylate the precursor. Translocation and glycosylation were partially restored by a high-salt extract prepared from yeast ribosomes. The results presented here suggest that yeast-specific factors are needed to translocate and glycosylate acid phosphatase efficiently in vitro.

Acid Phosphatase↗
PubMed1994

Characterization and sequence of PhoC, the principal phosphate-irrepressible acid phosphatase of Morganella morganii.

Phosphatase activities were investigated in Morganella morganii, which is one of the few enterobacterial species producing high-level phosphate-irrepressible acid phosphatase activity (HPAP phenotype), and the gene encoding the major phosphate-irrepressible acid phosphatase was cloned, sequenced, and its product characterized. Using p-nitrophenyl phosphate as substrate, Morganella produced a major phosphate-irrepressible acid phosphatase (named PhoC) which is associated with the HPAP phenotype, a minor phosphate-irrepressible acid phosphatase, and a phosphate-repressible alkaline phosphatase. The presence of the PhoC activity prevented induction of alkaline phosphatase when a PhoC-hydrolysable organic phosphate ester, such as glycerol 2-phosphate, was the sole phosphate source. PhoC is a secreted nonspecific acid phosphatase apparently composed of four 25 kDa polypeptide subunits. The enzyme is resistant to EDTA, P(i), fluoride and tartrate. The M. morganii PhoC showed 84.6% amino acid sequence identity to the PhoN nonspecific acid phosphatase of Providencia stuartii, 45.3% to the PhoN nonspecific acid phosphatase of Salmonella typhimurium, and 37.8% to the principal acid phosphatase (PhoC) of Zymomonas mobilis. Comparison of sequence data and of regulation of these enzymes suggested a different phylogeny of members of this gene family within the Enterobacteriaceae.

Acid Phosphatase↗
PubMed2006

Human breast cancer cell lines and tissues express tartrate-resistant acid phosphatase (TRAP).

Tartrate-resistant acid phosphatase (TRAP) is expressed by osteoclasts, macrophages and dendritic cells. TRAP has been identified in a wide variety of tissues, however, its biological function is not fully understood. Serum TRAP is a marker of diseases involving excessive bone resorption including metastatic bone disease in breast cancer patients and can be used to monitor responses to treatment. Our aim in this study was to determine whether TRAP is expressed by human breast tumours. Four breast cancer cell lines were assayed for TRAP activity. MDA-MB-435, the most tumourigenic line, had an activity twofold higher than the other cell lines. Immunohistochemistry using a TRAP specific antibody confirmed that both cell lines and human breast tumours express TRAP. Expression was absent in benign tissues and abundant in more aggressive tumours. This work suggests that tumour derived TRAP contributes to the raised enzyme activity found in the serum of breast cancer patients.

Acid Phosphatase↗