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PubMed2001

[Activity and thermal stability of acid phosphatase in homogenates of Amoeba proteus, acclimated to various temperatures].

Activity and thermoresistance of acid phosphatase were determined in supernatant of Amoeba proteus homogenates using 1-naphthyl phosphate (pH 4.0) and p-nitrophenyl phosphate (pH 5.5). Although tartrate-resistant and tartrate-sensitive acid phosphatases hydrolyse both substrates, the former mainly hydrolyses p-nitrophenyl phosphate and the latter 1-naphthyl phosphate. A decrease in the activity of the total and tartrate-sensitive acid phosphatases, when using 1-naphthyl phosphate, and of the total and tartrate-resistant acid phosphatases, when using p-nitrophenyl phosphate, was found in amoebae acclimated to 10 degrees C (10 degrees-amoebae) compared to those acclimated to 25 degrees C (25 degrees-amoebae). Using 1-naphthyl phosphate, the thermoresistance of the total acid phosphatase was lower in 10 degrees-amoebae than in 25 degrees-amoebae, but the thermostability of tartrate-resistant enzyme was the same in both groups of amoebae. Using p-nitrophenyl phosphate, the thermoresistance of the total and tartrate-resistant acid phosphatases was lower (the latter only slightly) in 10 degrees-amoebae than in 25 degrees-amoebae. It is suggested that at least with the use of 1-naphthyl phosphate a decrease in thermostability of the total acid phosphatase may be due to a decrease in thermoresistance of tartrate-sensitive enzyme. The results obtained confirm the author's previous data on the activity and thermostability of electrophoretic forms of acid phosphatase using 2-naphthyl phosphate in 10- and 25 degrees-amoebae (Sopina, 2001). It is the first case of discovering a correlation between changes in primary cell thermoresistance of amoebae cultured at different temperatures and changes in the activity and thermostability of acid phosphatase in their homogenates, with the number of electrophoretic forms of this enzyme and their mobility being permanent.

Acid Phosphatase↗
PubMed1985

Synthesis and transport of lysosomal acid phosphatase in normal and I-cell fibroblasts.

The biosynthesis, proteolytic processing, and transport of lysosomal acid phosphatase in normal and I-cell human skin fibroblasts was studied by metabolic labeling of the cells and isolation of acid phosphatase by immunoprecipitation. Several forms of the enzyme were identified in pulse-chase experiments. The largest precursor form had a Mr of 110,000. It was accompanied by several smaller polypeptides (Mr = 84,000-62,000), which were localized to light membranes containing the markers of endoplasmic reticulum and Golgi complex. These polypeptides were further processed to mature forms with apparent Mr of 57,000, 48,000, and 43,000 that accumulated in the cells and were associated with dense lysosomes. Less than 10% of newly synthesized acid phosphatase was secreted mainly as Mr = 112,000 and 74,000 forms. The processing of acid phosphatase was inhibited by NH4Cl and by a peptidyldiazomethyl ketone inhibitor of cysteine proteinases. The intracellular Mr = 110,000, 57,000, and 48,000 and the secreted Mr = 112,000 and 64,000 forms contained phosphorylated oligosaccharides cleavable by endo-beta-N-acetylglucosaminidase H. Transport of acid phosphatase into lysosomes was sensitive to NH4Cl and dependent on mannose 6-phosphate specific receptors by the following criteria: (i) inhibition of endocytosis of acid phosphatase by mannose 6-phosphate, (ii) enhancement of the secretion of acid phosphatase in the presence of antibodies to the mannose 6-phosphatase specific receptor, and (iii) secretion of about two-thirds of newly synthesized acid phosphatase in I-cell fibroblasts. Obviously, the mechanism of transport of acid phosphatase into lysosomes is indistinguishable from that operating for other lysosomal enzymes in fibroblasts. In contrast to other lysosomal enzymes, acid phosphatase appears to be subjected to an early proteolytic processing, presumably within the endoplasmic reticulum, which results in secretion of several processed forms of the enzyme.

Acid Phosphatase↗
PubMed1980

Light microscopic localization of acid phosphatase in different tissue cells of the albino rat.

The enzyme acid phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1 3.2), often referred to as "non-specific acid phosphomonoesterase" because of histochemical and biochemical polymorphisms and ubiquity, is one of the most thoroughly studied enzyme in mammalian tissues. The aim of the present work was to outline the functional characteristics of this enzyme by extrapolating the results of light microscopic investigations. A diffuse intracytoplasmic acid phosphatase activity was detected in the epinephrine-producing cells of the adrenal medulla. Various forms of lysosomes were observed to exert acid phosphatase activity in bronchial and bronchiolar epithelia, hepatocytes, Kupffer cells and in the walls of brain vessels. Pseudounipolar ganglion cells and certain neurons of the medulla oblongata were found to contain acid phosphatase in intracellular membrane systems. Biochemically, acid phosphatase consists of more than four isozymes each of them possessing antigenically diverse molecular forms suggesting molecular polymorphism. Histochemical and biochemical polymorphisms of acid phosphatase are considered to be due to the accommodation to the pleomorphic appearance of a sole chemical bond.

Adrenal Medulla↗
PubMed1988

Acid phosphatase activity of virulent and avirulent clones of Leishmania donovani promastigotes.

Virulent and avirulent clones of Leishmania donovani promastigotes were examined for their acid phosphatase activity. The acid phosphatase activity of whole-cell lysates of virulent clones was 1.5 to 2.0 times higher than that of avirulent clones. Pellet fractions (260,000 x g, 30 min) from sonicated promastigotes of a virulent clone and an avirulent clone contained 60 and 40% of the total enzyme activity, respectively. Membrane-bound acid phosphatase was extracted with Triton X-100 from the pellet. This membrane-bound phosphatase activity was 2.4-fold higher in virulent organisms than in avirulent organisms. The membrane acid phosphatase exhibited two distinct bands on polyacrylamide gels stained for enzyme activity. One diffuse, faster-migrating band showed identical electrophoretic mobility in both virulent and avirulent clones, although a higher enzymatic activity was observed with the extract from virulent cells. In contrast, a slower-migrating band was different between the two clones in the mobility. These results suggest that membrane-bound acid phosphatase was quantitatively and qualitatively different between virulent and avirulent promastigotes of L. donovani. In addition, virulent cells produced a relatively high level of acid phosphatase throughout the growth in culture.

Acid Phosphatase↗
PubMed1981

The significance of prostatic acid phosphatase in adenocarcinoma of the prostate.

Our radioimmunoassay for prostatic acid phosphatase was compared to commercial radioimmunoassay kits. A close correlation among all 3 assays was found in control groups, and in patients with benign prostatic hyperplasia and adenocarcinoma of the prostate. These results also were compared to recent reports from other centers using similar methodologies. In 7 to 15 per cent of the patients with bone metastasis normal levels of serum prostatic acid phosphatase were found. Variability in prostatic acid phosphatase production by the tumor may account for this finding. Elevated levels of prostatic acid phosphatase were associated more commonly with less differentiated primary tumors. A low percentage of prostatic acid phosphatase elevations in patients with early localized and incidental adenocarcinoma was found for the 3 assays evaluated. These factors, along with the falsely positive rates in patients with benign disease, limit severely the application of these assays to the screening of male patients at risk for adenocarcinoma of the prostate.

Acid Phosphatase↗
PubMed1988

Chick osteoblasts contain fluoride-sensitive acid phosphatase activity.

We used histological and biochemical methods to determine the cellular origin of bone matrix fluoride-sensitive acid phosphatase in chicken bone. Embryonic chicken calvariae were embedded in plastic and sections stained for acid phosphatase at various concentrations of substrate and fluoride. Acid phosphatase activity was observed in osteoblasts and osteoclasts but not in fibroblasts. Striking inhibition of osteoblastic acid phosphatase occurred at 100 microM fluoride, a concentration that had no apparent effect on osteoclastic acid phosphatase. Inhibition of osteoblastic and osteoclastic acid phosphatase by fluoride was also examined using extracts of embryonic chicken calvarial cells, mouse osteoblasts (MC3T3-El cell line), and purified chick osteoclasts, respectively. Fluoride is a partial competitive inhibitor of both chicken and mouse osteoblastic acid phosphatases, with apparent inhibition constants of 10-100 microM. These concentrations of fluoride correspond to those that increase bone formation in vitro and in vivo. In contrast, the apparent inhibition constant for fluoride of osteoclastic acid phosphatase was much higher (i.e., 0.5 mM). In summary, this study demonstrates that chicken osteoblasts contain an acid phosphatase that is sensitive to inhibition by low concentrations (i.e., microM) of fluoride.

Acid Phosphatase↗
PubMed1996

Localization of tartrate-resistant acid phosphatase in human placenta.

Tartrate-resistant acid phosphatase is an inducible marker of cell differentiation and activation expressed by specialized cells of macrophage lineage and some activated lymphocytes. Clinically, this phosphatase is a diagnostic marker for hairy cell leukaemia and osteoclast activity. The cDNA for this enzyme has been cloned from a placental expression library, yet the cell(s) expressing the enzyme protein has not been determined with certainty. Our laboratories have developed a monoclonal antibody, 9C5, suitable for immunohistochemical localization of tartrate-resistant acid phosphatase in paraffin sections. The purpose of this study was to use antibody 9C5 to identify cells expressing tartrate-resistant acid phosphatase in sections of paraffin-embedded, normal, full-term placenta and to determine if those cells expressed other macrophage markers including CD68 (PG-M1 antibody), LN5, lysozyme, alpha 1-antitrypsin and alpha 1-antichymotrypsin. Histochemical localization of activity in frozen sections was compared with immunohistochemical localization in paraffin sections of the same tissue specimens. The activity and antigenicity of this enzyme were detected in decidual cells, syncytiotrophoblast, and some macrophages distributed throughout maternal and embryonic tissues, but not in neutrophils. Unlike other tissues previously examined, placenta contains significant numbers of the phosphate-positive cells that are not of macrophage origin.

Acid Phosphatase↗
PubMed1989

Purification and characterization of a tartrate-resistant acid phosphatase from human osteoclastomas.

Tartrate-resistant acid phosphatase is one of the major enzymes produced and secreted by osteoclasts. To obtain sufficient enzyme for biochemical characterization, we have purified this enzyme from human osteoclastomas by sequential chromatography on SP-Sephadex, CM-Sephadex, hydroxylapatite, Sephadex G-150 and concanavalin A-Sepharose. The purification over the original tumour extract was about 2000-fold, with a yield of 10%. The enzyme appeared to be homogeneous when assessed by SDS/polyacrylamide-gel electrophoresis. Both gel filtration and SDS/polyacrylamide-gel electrophoresis indicated an Mr of about 30,000. The reduced and alkylated enzyme consists of two subunits with Mrs of 15,000 and 17,500. The N-terminal amino acid sequence of both subunits indicates that there is a high degree of identity between the osteoclastoma enzyme and similar enzymes purified from spleen and uterus. Using 4-methylumbelliferyl phosphate as substrate, the specific activity of the purified enzyme was 387 units.mg-1, and the Km was 284 microns. The pH optimum was 5.7. Unlike similar enzymes purified from human and bovine bone, osteoclastoma acid phosphatase is not activated by reducing agents (2-mercaptoethanol or ascorbic acid). The enzyme contains 4.8 mol of Fe2+/3+, 0.3 mol of Mn2+ and 1.7 mol of Mg2+ per mol of enzyme. Although the enzyme loses 50% of its activity in the presence of EDTA, it is not inhibited by the iron chelator 1,10-phenanthroline. However, the enzyme is activated to a small extent by Mn2+ and Mg2+. Using a variety of substrates and inhibitors, we demonstrate that there are differences between the osteoclastoma acid phosphatase and the enzyme purified from other sources.

Acid Phosphatase↗
PubMed1976

Importance of SH groups in catalysis by bovine brain acid phosphatase.

The rate of inactivation of acid phosphatase (EC 3.1.3.2) from bovine brain by dithiobis-(2-nitrobenzoic acid) (Nbs2) is identical to the rate of titration of one of the two SH groups of this enzyme. The rate of inactivation of the enzyme by Nbs2 is pH dependent and, at 300 mM NaCl, can be described by the reaction of a single SH group of pK 8.4. At low ionic strength the pK determined from the k inactivation vs. pH profile is 7.7 and the results deviate markedly from the predicted values at pH values less than or equal to 6. The decrease of V upon addition of salts is paralleled by the decrease of inactivation rate by Nbs2. The relevance of SH groups in catalysis by bovine brain acid phosphatase is discussed in terms of these data.

Acid Phosphatase↗
PubMed1988

Purification and characterization of acid phosphatase from cotyledons of germinating soybean seeds.

Soybean acid phosphatase (orthophosphoric-monoester phosphohydrolase, EC 3.1.3.2) was completely separated from phytase (EC 3.1.3.8) isolated from cotyledons of germinating seeds and purified to homogeneity. A four-step purification regimen consisting of ammonium sulfate fractionation, and ion-exchange, affinity, and chromatofocusing gel chromatographies was employed to achieve a homogeneous preparation. Acid phosphatase activity appeared as a major band of the three forms of acid phosphatase identified on native gels. The purified enzyme had a molecular weight of 53,000 when electrophoresed on 8% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a molecular weight of 53,000 from its mobility in a Fracto-gel TSK HW-50F gel permeation column. The molar extinction coefficient of the enzyme at 278 nm was estimated to be 4.2 X 10(4) M-1 cm-1. The isoelectric point of the protein, as revealed by chromatofocusing, was about 6.7. The optimal pH for activity, like other plant acid phosphatases, was 5.0. While the enzyme failed to accommodate phytate as a substrate, the enzyme did exhibit a broad substrate selectivity. The affinity of the enzyme for p-nitrophenyl phosphate was high (Km = 70 microM), and activity was competitively inhibited by orthophosphate (Ki = 280 microM). The estimated catalytic turnover number (Kcat) of the enzyme for p-nitrophenyl phosphate was about 430 per second. Although the purified enzyme was stable at 0 degrees C and exhibited maximum catalytic activity at 60 degrees C, thermal inactivation studies indicated that the enzyme lost 100% activity after treatment at 68 degrees C for 10 min.

6-Phytase↗
PubMed1990

Comparison of tartrate resistant acid phosphatase in a giant cell bone tumor and a spleen infiltrated with hairy cells.

Acid phosphatase (E.C.3.1.3.2) in a giant cell bone tumor and a spleen infiltrated with hairy cells was extracted by citrate buffer and then by 0.3 mol/L NaCl. The cationic acid phosphatase in the crude extract was isolated by CM-cellulose chromatography, and further separated by high pressure liquid chromatography. The majority of the tartrate resistant acid phosphatase in the hairy cell spleen was unabsorbed on CM-cellulose and was insensitive to iron. A much larger portion of the acid phosphatase in the bone tumor, than in the spleen, was cationic and was eluted from the column by 0.8 mol/L NaCl. The cationic acid phosphatase was further separated into consecutive peaks of acid phosphatases with different sensitivity to iron. A major portion of acid phosphatase in the giant cell bone tumor was enhanced by iron, while the amounts of iron-enhanced and iron-insensitive acid phosphatase were about the same in the spleen. The differences of the phosphatases in these two types of pathologic specimens indicate the occurrence of two types of enzymes with different biological significance.

Acid Phosphatase↗
PubMed1983

Correlation between extent of metastatic lesions in whole body bone scintigraphy of patients with prostatic cancer and prostatic acid phosphatase in serum with Eiken PAP RIA kit.

The whole body bone scintigraphy of 13 patients whose prostatic cancer were histologically confirmed, was processed in four colors, and the bone metastases were quantitatively estimated. On the basis of this estimation, the extent of bone metastases was classified into 4 divisions (grades 0, 1, 2 and 3). And then, the correlation between the extent of bone metastases and prostatic acid phosphatase, acid phosphatase, and alkali phosphatase levels in serum were investigated.

Acid Phosphatase↗
PubMed1978

The significance of bone marrow acid phosphatase in patients with prostatic carcinoma.

The levels of total and l-tartrate labile acid phosphatase were studied in 49 patients with prostatic carcinoma. The results were compared with the results from a control group. The acid phosphatase levels from the bone marrow were above the upper normal limit of serum acid phosphatase both in the control group and in patients with prostatic carcinoma. This may be due to acid phosphatase released from blood cells during haemolysis. There was a positive correlation between serum and bone marrow acid phosphatase levels in patients with prostatic carcinoma. Significantly raised levels of bone marrow acid phosphatase (above the upper limit of the normal range from the control group) were observed only in advanced stage IV patients with significantly increased serum levels. The levels of bone marrow acid phosphatase gave no supplementary diagnostic information in any of the patients with prostatic carcinoma. Doubt is expressed concerning the hypothesis that raised levels of bone marrow acid phosphatase are diagnostic of early metastases from prostatic carcinoma.

Acid Phosphatase↗
PubMed1968

Isozymes of acid phosphatase in normal and Calmette-Guérin bacillus-induced rabbit alveolar macrophages.

The acid phosphatase activity of normal alveolar and BCG-induced alveolar macrophages has been examined. Five electrophoretically distinct forms of acid phosphatase have been identified in both normal and BCG-induced macrophages. The acid phosphatases can be divided into two major categories. One category, containing four distinct forms, is readily solubilized after repeated freezing and thawing or mechanical disruption The second category, containing one form, is firmly bound to the lysosomal membrane and can be solubilized by treatment of the lysosomal fraction with Triton X-100. The Triton-extractable acid phosphatase and the predominant aqueous soluble acid phosphatase have been shown to differ in the degree of membrane binding, in solubility, in net charge, and in molecular weight. The two pre-dominant phosphatases possess identical pH optimum and do not differ in response to enzyme inhibitors. BCG stimulation has been shown to result in a nearly twofold increase in acid phosphatase activity. A nearly proportionate increase in the major acid phosphatase forms has been observed.

Acid Phosphatase↗
PubMed1983

Circadian variation of different fractions of serum acid phosphatase.

The circadian variation of different fractions of serum acid phosphatase was determined in two men with a normal prostate, two men with benign prostatic hyperplasia, and four men with prostatic cancer. Serum samples were obtained every 2 hours from 8:00 a.m. until 6:00 a.m. the following day. An overall sample standard deviation of 1.98 U/liter was calculated for total acid phosphatase, 0.4 U/liter for tartrate-labile acid phosphatase, and 0.13 micrograms/liter for prostatic acid phosphatase as determined by immunoenzyme assay.

Acid Phosphatase↗
PubMed1997

Two tandemly arrayed genes encode the (histidine) secretory acid phosphatases of Leishmania donovani.

Leishmania donovani promastigotes constitutively secrete a glycosylated and phosphorylated acid phosphatase activity. This secretory acid phosphatase (SAcP) was purified from L. donovani culture supernatants and amino-acid sequence was obtained from both the N-terminus and a tryptic peptide fragment derived from the isolated protein. A polymerase chain reaction (PCR)-based strategy, using degenerate oligo primers designed from the amino-acid sequence data, identified two single-copy, tandemly arrayed open reading frames (ORFs) capable of encoding the L. donovani SAcP (SAcP-1, 2052 bp and SAcP-2, 2124 bp). Both SAcP-1 and -2 were shown to be actively transcribed by L. donovani promastigotes by reverse transcription (RT) and PCR amplification. The deduced amino-acid sequences of SAcP-1 and SAcP-2 show high conservation to each other in four regions: a 23-amino-acid signal peptide; a catalytic domain containing several potential N-linked glycosylation sites; a Ser/Thr-rich repeat region containing multiple potential phosphorylation sites and a common C-terminus. Within the catalytic domain, the L. donovani SAcPs possess two conserved consensus sequences characteristic of histidine acid phosphatases (AcPs). Furthermore, antisera to native L. donovani SAcP immunoprecipitated in vitro transcription/translation products of both SAcP-1 and SAcP-2. Cumulatively, these data indicate that the acid phosphatase activity constitutively secreted by L. donovani promastigotes is composed of two (histidine) AcP isoforms that are encoded by SAcP-1 and SAcP-2, respectively.

Acid Phosphatase↗
PubMed2005

Arabidopsis vegetative storage protein is an anti-insect acid phosphatase.

Indirect evidence previously suggested that Arabidopsis (Arabidopsis thaliana) vegetative storage protein (VSP) could play a role in defense against herbivorous insects. To test this hypothesis, other AtVSP-like sequences in Arabidopsis were identified through a Basic Local Alignment Search Tool search, and their transcriptional profiles were investigated. In response to methyl jasmonate application or phosphate starvation, AtVSP and AtVSP-like genes exhibited differential expression patterns, suggesting distinct roles played by each member. Arabidopsis VSP2 (AtVSP2), a gene induced by wounding, methyl jasmonate, insect feeding, and phosphate deprivation, was selected for bacterial expression and functional characterization. The recombinant protein exhibited a divalent cation-dependent phosphatase activity in the acid pH range. When incorporated into the diets of three coleopteran and dipteran insects that have acidic gut lumen, recombinant AtVSP2 significantly delayed development of the insects and increased their mortality. To further determine the biochemical basis of the anti-insect activity of the protein, the nucleophilic aspartic acid-119 residue at the conserved DXDXT signature motif was substituted by glutamic acid via site-directed mutagenesis. This single-amino acid alteration did not compromise the protein's secondary or tertiary structure, but resulted in complete loss of its acid phosphatase activity as well as its anti-insect activity. Collectively, we conclude that AtVSP2 is an anti-insect protein and that its defense function is correlated with its acid phosphatase activity.

Acetates↗
PubMed2002

[Effect of phosphorus deficiency on activity of acid phosphatase exuded by wheat roots].

The activity of acid phosphatase exuded by roots, the tissue location of the enzyme, and the relationship between the enzyme activity and phosphorus efficiency of wheat were studied. The results showed that the activity of acid phosphatase exuded by wheat 81(85)5-3-3-3 and NC37 under P-sufficiency treat were lower than those under P-deficiency, and the enzyme activity of the former variety was significantly higher than that of the latter. There was a significant difference in the enzyme activity among 12 wheat genotypes grown under P-deficiency treat. Acid phosphatase was exuded by epidermis cell of root, especially by epidermal cell of root apex. Thus, there was a linear relationship between the enzyme activity and the surface area of root or the number of root apexes. It implied that the enzyme activity was markedly related to the size of root system. The linear relationship between relative grain yield and acid phosphatase activity was significant. It indicates that the enzyme activity could be used as an early indicator to select P-efficient wheat genotypes.

Acid Phosphatase↗