Dimeric nature and amino acid compositions of homogeneous canine prostatic human liver and rat liver acid phosphatase isoenzymes. Specificity and pH-dependence of the canine enzyme

Characterization of a novel acid phosphatase from embryonic axes of kidney bean exhibiting vanadate-dependent chloroperoxidase activity

A novel colorless acid phosphatase (KeACP), which was distinct from the kidney bean purple acid phosphatase, was purified to apparent homogeneity and cloned from embryonic axes of kidney bean (Phaseolus vulgaris L. Ohfuku) during germination. When orthovanadate (VO(4)(-3)) is added to the apo form of the enzyme, KeACP uniquely exhibits the chloroperoxidase activity with loss of phosphatase activity. This is the first demonstration that KeACP is a vanadate-dependent chloroperoxidase in plants to be characterized and suggests that KeACP may play a role in modifying a wide variety of chlorinated compounds that are present in higher plants. The enzyme is a dimer that presents three forms made up of the combination of the dominant 56-kDa and the minor 45-kDa subunits, and both subunits contain carbohydrate. The full-length cDNA of the KeACP gene is 1641 nucleotides, and this sequence is predicted to encode a protein having 457 amino acid residues (52,865 Da), including a signal peptide. The complete nucleotide sequence of the genomic DNA (3228 bp) of KeACP consists of seven exons and six introns. Northern blot analysis demonstrated that the KeACP gene was expressed specifically in embryonic axes of the kidney bean, and its expression coincided with elongation of the embryonic axis during germination.

Characterization of the type of carbohydrate chains of the higher molecular weight (140 kDa) acid phosphatase of the frog liver

1. The higher molecular weight, (HMW, M(r) 140 kDa) acid phosphatase (AcPase) of the frog liver (Rana esculenta) was separated into enzymatically active components by isoelectric focusing in an immobilized pH gradient and their carbohydrate chains were analyzed by specific lectin binding after native blotting. 2. The lectin-binding patterns obtained with ConA, WGA, LcH and PNA as well as with WGA and PNA after desialylation indicate that the frog liver HMW AcPase contains predominantly N-linked complex and/or hybride type carbohydrate chains with terminal sialic acid and fucose residues; O-glycosylated enzyme components with free and sialic acid substituted Gal-GalNAc sequences were also detected.

Acid phosphatases in mammalian tissues. Evidence for the existence of a 57 kDa Zn(2+)-dependent acid phosphatase form

1. A comparative study of multiple forms of acid phosphatase (AcPase) in various organs of mammals was carried out. 2. These studies indicated that the high-molecular weight AcPase is preferentially expressed by tissues which undergo cell proliferation such as epithelial tissues; on the contrary, the low-molecular weight enzyme seems to be characteristic of highly differentiated tissues such as nervous, muscle and blood erythrocytes. 3. The existence of a new AcPase activated by Zn2+ ions was observed in all tissues studied with the exception of erythrocytes. 4. The enzyme shows a molecular weight of 57 kDa, is insensitive to NaF, hydrolyzes p-nitro-phenylphosphate and o-c-phenylphosphate; ATP, a-naphthyl-phosphate and beta-glycerolphosphate are also dephosphorylated.

Isolation and characterization of a homogeneous isoenzyme of wheat germ acid phosphatase

An acid phosphatase (orthophosphoric monoester phosphohydrolase, acid optimum; EC 3.1.3.2) isoenzyme from wheat germ was purified 7000-fold to homogeneity. The effect of wheat germ sources and their relationship to the isoenzyme content and purification behavior of acid phosphatases was investigated. Extensive information about the purification and stabilization of the enzyme is provided. The instability of isoenzymes in the latter stages of purification appeared to be the result of surface inactivation together with a sensitivity to dilution that could be partially offset by addition of Triton X-100 during chromatographic procedures. Added sulfhydryl protecting reagents had no effect on activity or stability, which was greatest in the pH range 4-7. The purified isoenzyme was homogeneous by polyacrylamide gel electrophoresis and exhibited the highest specific activity and turnover number reported for any acid phosphatase. The molecular weights of the pure isoenzyme and of related isoenzymes from wheat germ were found to be identical (58,000). The pure isoenzyme contained a single polypeptide chain and had a negligible carbohydrate content. The amino acid composition was determined. Of the various reasons that were considered to explain isoenzyme occurrence, a genetic basis was considered most likely. The enzyme was found to exhibit substrate inhibition with some substrates below pH 6, while above pH 8 it exhibited downwardly curving Lineweaver-Burk plots of the type that are generally described as "substrate activation". The observation of a phosphotransferase activity was consistent with the formation of a covalent phosphoenzyme intermediate, while inactivation by diethyl pyrocarbonate was consistent with the presence of an active site histidine.

Acid phosphatases in the frog (Rana esculenta) skeletal muscle. Purification and some properties of the low molecular weight enzyme

1. The presence of high-Mr and low-Mr acid phosphatases [orthophosphoric-monoester phosphohydrolase, (acid optimum), EC 3.1.3.2] in the skeletal muscle of frog Rana esculenta was reported. 2. The subcellular localization and some characteristics of both enzymes were also described. 3. The low-Mr AcPase was purified to homogeneity. The enzyme did not absorb on Concanavalin A-Sepharose 4B indicating that this was not a glycoprotein. 4. The enzyme is homogeneous on polyacrylamide gel electrophoresis and moves as a single band of Mr 13.7 +/- 0.8 kDa in the presence of sodium dodecyl sulphate. 5. The Mr of the native enzyme was 14.0 +/- 1.1 kDa as determined by gel filtration on a Sephadex G-100 column. The isoelectric point was 6.02. 6. The enzyme was strongly inhibited by 1 mM Ag+, Hg2+, Sn2+ and Cu2+ while other cations both at 10(-2) and 10(-3) M showed little or no effect. 7. The enzyme was insensitive to NaF and tartrate but was strongly deactivated by formaldehyde, PMB, Iodoacetamide and Triton X-100. Phosphate was a competitive inhibitor (k1 = 0.83 mM). 8. The best substrate for the enzyme was p-nitrophenylphosphate but phenylphosphate, flavin mononucleotide and o-P-tyrosine were also hydrolyzed, though at different rates. 9. The enzyme activity was enhanced in the presence of methanol, ethanol, acetone and glycerol indicating a phosphotransferase activity.

Studies on the oligosaccharide heterogeneity of the isoelectric forms of the lower molecular weight acid phosphatase of frog liver

1. The lower molecular weight, heterogeneous acid phosphatase (AcPase) from the frog liver (Rana esculenta) containing AcPase I, II, III and IV was separated into enzymatically active components by isoelectric focusing in an immobilized pH gradient. 2. The blotted enzyme bands were characterized by their different binding patterns obtained with the lectins concanavalin A, wheat germ agglutinin (WGA), Lens culinaris hemagglutinin (LcH) and peanut agglutinin (PNA). 3. In situ neuraminidase treatment reduced the staining intensity of some WGA-bands and increased that of PNA-bands. 4. The finding that AcPases I, II, III and IV differ in their carbohydrate chain composition, together with previous results showing different bioactivities of AcPases III and IV, indicates a correlation between the glycosylation state of enzyme forms and their physiological action.

Purification and subcellular localization of Zn-dependent acid p-nitrophenylphosphatase in frog liver and comparison with other vertebrates

Zn2(+)-dependent acid p-nitrophenylphosphatase (Zn-AcPase) from liver of Rana esculenta was purified to homogeneity. The purified enzyme moves as a single electrophoretic band at pH 8.3 in 7.5% acrylamide and was coincident with the enzyme activity. The enzyme has a molecular weight of 102,000 +/- 5,000D and is a dimer with two apparently similar polypeptide chains of 48,000 +/- 3,000D as determined by sodium dodecylsulfate gel electrophoresis. Zn-AcPase from frog liver requires Zn2+ ions for catalytic activity; other bivalent cations have little or no effect. The enzyme with a pI of 7.07 does not appear to be a glycoprotein and was associated with the soluble fraction after liver cell fractionation. The biochemical and molecular properties of frog liver Zn-AcPase were compared with that of the enzyme partially purified from carp (Cyprinus carpio), pike (Esox lucius), and rat (Rattus norvegicus).

Multiple forms of barley root acid phosphatase: purification and some characteristics of the major cytoplasmic isoenzyme

The major acid phosphatase form (orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2) was purified from the soluble extract of barley roots. The enzyme is homogeneous on polyacrylamide gel electrophoresis and moves as a single band of Mr approximately 38,000 in the presence of sodium dodecyl sulphate. The molecular weight of the native enzyme was Mr 77,600 and 79,000 as determined, respectively, by gel filtration on a Sephadex G-100 column and by density gradient ultracentrifugation. The isoelectric point was about 6.28. The enzyme is competitively inhibited by molybdate (Ki = 9 x 10(-7) M). NaF, Ag(+), Hg(2+), Pb(2+) and Zn(2+) are also inhibitors, while other cations showed no effect. The enzyme hydrolyzes a wide variety of natural and synthetic phosphate esters. In particular, the enzyme seems to be active on ATP, o-phosphotyrosine, o-phosphoserine and glucose 1-phosphate. The pH dependence studies between pH 4-8 using p-nitrophenylphosphate as substrate and diethylpyrocarbonate inactivation indicate the presence of essential histidine residue at the active site.

Phosphotyrosine phosphatase activity of human and canine acid phosphatases of prostatic origin

Human and canine prostatic specimens containing high levels of acid phosphatase (AP) activity were tested, at acid pH, for their ability to hydrolyze the major phosphoaminoacids present in phosphorylated proteins, phosphoserine (p-ser), phosphothreonine (p-thr), and phosphotyrosine (p-tyr). The cleavage of a synthetic substrate, para-nitrophenyl-phosphate (p-npp), was also measured as an indicator of AP activity; its inhibition by sodium-L-tartrate (T) was used as a criterion to identify prostatic acid phosphatase (PAP). It was found that: 1) the Km of p-tyr and p-npp were 2.0 mM and 0.41 mM, respectively, with similar Vmax values (0.078 and 0.087 mumoles of phosphate (Pi) liberated per minute per milligram of protein); 2) the ID50 were 0.25 mM and 0.50 mM with sodium orthovanadate (VO4) and T, respectively, using p-npp as substrate-with p-tyr as substrate, the values obtained were 0.016 mM and 0.11 mM, respectively; 3) activity toward p-ser and p-thr was minimal; 4) native PAP from dog seminal plasma, with a molecular weight of 90-100 kD, as determined by gel filtration on HPLC, hydrolyzed p-tyr preferentially, and this phosphatase (Pase) activity was also strongly inhibited by both T and VO4; and 5) the AP present in human and canine prostatic tissue and cells, as well as in their secretions, also preferentially hydrolyzed phosphotyrosine, and it was inhibited by T and VO4. It is proposed that these p-tyr Pases may be involved in the local regulation of prostatic growth.

Demonstration of prostatic-type acid phosphatase in non-lysosomal granules in the crypt epithelium of the human duodenum

Human prostatic-type of acid phosphatase has been demonstrated by biochemical methods to be expressed in a number of cells and tissues in addition to the prostate gland. However, the function of this activity is unknown, nor has the enzyme been convincingly localized at the cellular level in any non-prostatic tissues. Using biochemical and immunocytochemical methods, we demonstrate that human intestinal epithelium contains both a lysosomal and prostatic type of acid phosphatase. The prostatic-type enzyme is present only in the epithelium of the crypts and to a lesser extent in the transitional zone at the base of the villi, in contrast to the widely-distributed lysosomal type. The prostatic enzyme is contained in granules that do not react with anti-lysosomal acid phosphatase and are probably secretory in nature.

Cytochemistry and biochemistry of acid phosphatases VII: Immunohistochemistry of canine prostatic acid phosphatase

Acid phosphatase (E.C. 3.1.3.2.) has been isolated from canine prostatic gland homogenates by gel permeation chromatography (AcA34 or G150), by affinity chromatography (con A-Sepharose), or by using fluid phase liquid chromatography (FPLC) using Superose 12 and Mono P columns. Acid phosphatase-enriched fractions were submitted to analytical SDS-PAGE or to analytical isoelectric focusing. A protein with a molecular weight of 30 kD (on SDS gels) was used for immunization of rabbits. The antiserum produced was cross-reactive with prostatic acid phosphatase (canine and human) as shown by immunoblotting. When applied to paraffin or plastic sections of normal canine prostate, a positive immunoreaction was found exclusively in the secretory cells. In experimentally altered glands (castration and/or hormone treatment), a varying pattern of immunoreactive cells was found. In canine prostatic carcinomas, intensively reacting cell clusters were found along with nonreactive cells. The antiserum was also slightly cross-reactive with the respective human antigen, but the cross-reactivity of an antiserum prepared against human prostatic secretory acid phosphatase with canine prostatic acid phosphatase was far more pronounced.

The presence of a Zn2+-dependent acid p-nitrophenyl phosphatase in bovine liver. Isolation and some properties

The presence of a Zn2+-dependent acid p-nitrophenyl phosphatase (EC 3.1.3.2) in bovine liver was described. The enzyme was purified to apparent homogeneity and migrates as a single band during electrophoresis on polyacrylamide gel. The enzyme requires Zn2+ ions for catalytic activity, other bivalent cations have little or no effect. The enzyme, of Mr 118,000, optimum pH 6-6.2 and pI 7.4-7.5, was inhibited by EDTA, tartrate, adenine and ATP, but not by fluoride. The common phosphate esters are poor substrates for the enzyme, which hydrolyses preferentially p-nitrophenyl phosphate and o-carboxyphenyl phosphate. The Zn2+-dependent acid p-nitrophenyl phosphatase of bovine liver was different from the high-Mr acid phosphatases previously detected in mammalian tissues.

Catfish liver acid phosphatases: differently glycosylated enzyme molecules with altered kinetic properties

Two forms of catfish liver acid phosphatase (AcPase I and II) were separated and purified to homogeneity and their carbohydrate compositions and some biochemical properties were studied. Evidence is given that AcPase I and II are differently glycosylated forms of the same enzyme. The enzyme forms differ significantly in the size and the composition of their carbohydrate components, sensitivity towards sulfhydryl-blocking and protecting reagents, sensitivity to ferric and ferrous ions, thermostability and ability to hydrolyze some nucleotides. The more highly glycosylated form is more sensitive to thermal denaturation. AcPase I and II behave differently towards ascorbate and changes in its concentration and it is suggested that the concentration of reducing modifiers may regulate AcPase activity at the cellular level. It is hypothesized that the differing extents of glycosylation influence the structure of the enzyme forms. This is expressed in altered conformations of two enzyme forms and results in a different exposure of the essential cysteine residues.

Biosynthesis of prostatic acid phosphatase in a normal human cell-line

The biosynthesis of the prostatic form of human acid phosphatase was studied in normal embryonic lung cells, WI-38, by metabolic labeling with tritiated leucine and [32P]phosphate, followed by specific immunoprecipitation, gel electrophoresis, and fluorography. Of the total tartrate-inhibitable acid phosphatase activity in WI-38 cells, 30% is due to the prostatic form. The primary translation product that leads eventually to the mature prostatic enzyme is a precursor polypeptide of 112 kDa. The precursor polypeptide is processed to mature polypeptides of 59, 55, and 49 kDa via an intermediate 91-kDa precursor. WI-38 cells also secrete a 113-kDa peptide into the medium. The precursor and mature polypeptides are glycosylated and phosphorylated. Upon treatment with endo-beta-hexosaminidase H, the apparent molecular weighs of the polypeptides are reduced by approximately 4 kDa and phosphate is lost.

Biosynthesis and processing of lysosomal acid phosphatase in cultured human cells

The biosynthesis of lysosomal acid phosphatase was studied in a normal human embryonic lung cell line, WI-38. Cells were labeled with radioactive leucine under a variety of conditions, the enzyme was immunoprecipitated using a monospecific antiserum raised against human liver lysosomal acid phosphatase, and the products were separated by electrophoresis and were visualized by fluorography. Lysosomal acid phosphatase constitutes 60% of the total tartrate-inhibitable acid phosphatase in WI-38. It is initially synthesized as a high-molecular-weight precursor polypeptide of 69 kDa. The precursor polypeptide is rapidly glycosylated and processed to a mature enzyme of 53-45 kDa via intermediates of 65 and 60 kDa in WI-38 cells. The 69-kDa precursor polypeptide is also converted to larger precursor polypeptides of 74 and 80 kDa. The multiplicity of precursor polypeptides is due at least in part to differences in the glycosylation and phosphorylation of the polypeptides. Sensitivity of phosphorylated oligosaccharide chains from precursor, mature and small polypeptides to endo-beta-hexosaminidase H-catalyzed cleavage suggests the presence of high-mannose phosphorylated oligosaccharide chains similar to those present on many other lysosomal enzymes. The effects of tunicamycin and ammonium chloride were also studied. In contrast to the effect of ammonium chloride on arylsulfatase A secretion, the lysosomal acid phosphatase in WI-38 cells was not secreted in the presence of NH4Cl. This is consistent with the existence of an alternate route for the transfer of lysosomal acid phosphatase into lysosomes. This alternate route may be the reason that I-cell fibroblasts contain a normal level of lysosomal acid phosphatase.

Immunological characterization of human acid phosphatase gene products

The immunological cross-reactivity of heterogeneous acid phosphatase isozymes from different human tissues has been studied using monospecific antisera prepared against four homogeneous acid phosphatases. The enzyme characterized as tartrate-inhibitable, prostatic acid phosphatase is also found to be present in leukocytes, kidney, spleen, and placenta. The tartrate-inhibitable (liver) lysosomal enzyme is also found in kidney, fibroblasts, brain, placenta, and spleen, but it is not detectable in erythrocytes and prostate. In several tissues, 10-20% of the tartrate-inhibitable enzyme is not precipitated by any of the antisera used; an exceptionally high amount (54%) of such an enzyme is present in human brain. Antiserum against a low molecular weight tartrate-resistant liver enzyme (14 kDa) does not crossreact with the erythrocyte enzyme. (10-20 kDa). All other tissues except placenta, prostate, and fibroblast cells show a cross-reactivity with the 14-kDa acid phosphatase antiserum. Thus, the low molecular weight human liver acid phosphatase is distinct from the erythrocyte enzyme, and there are also at least three different tartrate-inhibitable acid phosphatases in human tissues. Chromosomal assignments have been made for only two of the (at least) five acid phosphatases that are present in adult human tissues.

Isolation and partial characterization of high and low molecular weight acid phosphatases from chicken liver

Two acid phosphatase forms were isolated from chicken liver by gel filtration on Sephadex G-100. These enzymes, termed I and II, have similar Km- and Vmax-values, but differ in molecular weight, optimum pH, sensitivity to various inhibitors and substrate specificity. The results were compared with the numerous literature reports of mammalian acid phosphatases.

Raman and infrared studies of homogeneous forms of acid phosphatase from rat liver

Raman spectra of acid phosphatase (orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2) forms from rat liver in water solution, and infrared spectra of the same forms as thin films, have been investigated. The spectra show strong bands belonging to phosphodiester or phosphomonoester residues. These groups are modified during the postsynthetic modification of acid phosphatase and are probably connected with the process of bonding and splitting of mannose 6-phosphate and N-acetylglucosamine, in agreement with previous biochemical models for the intracellular transport of newly synthesized lysosomal hydrolases to lysosomes. Some other bands in the infrared spectra are assigned to vibrations of N-H groups which may belong to N-acetylglucosamine.

Identification of arginine esterase as the major androgen-dependent protein secreted by dog prostate and preliminary molecular characterization in seminal plasma

This work was undertaken to determine the identity of the major androgen-dependent 15,000 molecular weight protein previously observed on SDS polyacrylamide gel electrophoresis of both dog prostate cytosol and dog seminal plasma. The protein was identified as one of the two chains of arginine esterase on the basis of its ability to bind 3H-diisopropylphosphofluoridate (DFP), an active site titrant of serine proteases. Furthermore, since the other polypeptide chain was heterogeneous, at least five distinct peaks of arginine esterase activity could be separated by chromatofocusing under nonreducing conditions. The molecular weight of the seminal plasma protein was estimated at 29,500 by Sephadex G-100 gel filtration, and at 25,000 by SDS polyacrylamide gel electrophoresis in the absence of mercaptoethanol. In the presence of mercaptoethanol, two major peaks were observed with molecular weights of 15,000 and 14,000. These results show that arginine esterase of dog seminal plasma is a serine protease composed of two different chains linked by disulfide bridges. One of the chains contains the reactive serine group. The other one is probably glycosylated since it presents several isoelectric points.

Induction of acid phosphatase synthesis in canine prostatic epithelial cells in vitro

The increase in acid phosphatase (AP) activity in cultured canine prostatic epithelial cells was investigated as a biochemical marker of in vitro cellular differentiation. The enzyme was studied in secretory and non-secretory epithelial cell populations obtained from control and cycloheximide-treated cultures over a period of 3 weeks and compared to the AP present in tissue and cellular extracts from normal canine prostates. The progressive increase in AP activity with the duration of culture was strongly inhibited by cycloheximide in both cell populations. The degree of inhibition was more pronounced late in the culture when AP activity increased at a faster rate in secretory cells. Cycloheximide inhibited protein biosynthesis by 70-80% as evidenced by a reduction in the incorporation of amino acids into acid-insoluble material. However, the specific activities of AP in the cellular extracts were similar in control and cycloheximide-treated cultures and increased sharply by 3-4-fold in the secretory cells after 12 days of culture. When extracts derived from control and cycloheximide-treated cells of various duration were submitted to electrophoresis in polyacrylamide gels (PAGE), a unique pattern of three bands of AP activity with Rf values of 0.18, 0.27 and 0.38 was obtained. In controls the AP activity in the band with an Rf of 0.18 increased preferentially during the culture period and was more important quantitatively in secretory cells. In cycloheximide-treated cultures the increase of AP activity associated with the band with an Rf of 0.18 was more strongly inhibited. The addition of tartrate to the staining mixture inhibited all three bands of AP activity. Similar results were obtained when extracts derived from freshly dispersed cells as well as from normal canine prostatic tissue were submitted to PAGE; the AP activity was resolved into 3 bands with Rf values of 0.15-0.18, 0.23-0.27 and 0.33-0.38; all three bands were inhibited by the addition of tartrate and the first band was predominant. Thus, the increase in AP activity in prostatic epithelial cells in a culture medium supplemented with serum and deprived of sex steroids is due to the de novo synthesis of a major form of the enzyme by the secretory cells.

A clinical assay for prostatic acid phosphatase using choline phosphate as a substrate: comparison with thymolphthalein phosphate

We describe an assay method using choline O-phosphate as a substrate for the measurement of serum prostatic acid phosphatase as an aid in the diagnosis of prostatic cancer. Choline phosphate is hydrolyzed by homogeneous prostatic acid phosphatase, and it is also hydrolyzed by an acid phosphatase present in the serum of prostatic carcinoma patients. In contrast, serum samples from apparently healthy persons do not exhibit any significant choline O-phosphate phosphatase activity. There is a correlation of 98% (n = 46) between choline O-phosphate phosphatase activity and typical measurement for prostatic acid phosphatase activity carried out using thymolphthalein monophosphate as the substrate. The new method appears to be as accurate as colorimetric methods based on thymolphthalein phosphate as a substrate. Although not as sensitive as immunologically based methods, the present technique for measuring prostatic acid phosphatase activity using choline phosphate as a substrate is economical and relatively simple.

An essential carboxylic acid group in human prostate acid phosphatase

Treatment of homogenous human prostatic acid phosphatase (orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2) with low concentrations of Woodward's reagent K (N-ethyl-5-phenylisoxazolium-3'-sulfonate) leads to a rapid loss of enzymic activity. The rate of inactivation of the enzyme is reduced in the presence of the competitive inhibitors phosphate and L-(+)-tartrate, but not in the presence of non-inhibitory D-tartrate. Measurement of the ethylamine produced upon hydrolysis of enzyme modified in the presence of D- and of L-tartrate permitted the quantitative estimation of the number of carboxylic acid residues at the active site. The data indicate that two carboxyl groups per (dimeric) enzyme molecule are essential for catalytic activity. It is proposed that one function of the active site carboxyl group may be to protonate the leaving alcohol or phenol portion of the phosphomonoester substrate during the formation of the covalent phosphoenzyme intermediate.