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Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Disc-electrophoretic investigations of psoriatic scale homogenates (15000 x g supernatant) revealed several different phosphatase activities. At pH 5 either five different phosphatase active bands (substrates: p-nitrophenylphosphate, naphthylphosphate) or three different bands (substrate: glycerophosphate) could be obtained. At pH 7 only one band (substrate: p-nitrophenylphosphate) showed phosphatase activity. At pH 9.9 either two bands (substrate: p-nitrophenylphosphate) or three bands (substrate: glycerophosphate) could be demonstrated. the acid p-nitrophenylphosphatase activity of the psoriatic specific bands "9" and "10" could be distinguished by their different fluoride and tartrate susceptibility. Also the alkaline glycerophosphatase activities could be differentiated by distinct Ca and Mg susceptibility.
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PMID:Separation and molecular weight estimation of phosphatases in psoriatic scales by disc-electrophoresis. 23 77

1. Alkaline phosphatase (EC 3.1.3.1) from human liver was solubilized from the homogenate using 0.2% Triton X-100 containing 0.2 M lithium 3,5-diiodosalicylate, and the pellet obtained was resolubilized with 20% n-butanol. The procedure resulting in 3842-fold purification included acetone fractionation, ammonium sulfate precipitation, DEAE-cellulose chromatography, Sephadex G-200 gel filtration, hydroxyapatite gel chromatography and further concanavalin A/Sepharose 4B affinity chromatography. 2. The highly purified enzyme showed one major protein band on acrylamide gel electrophoresis at pH 8.6, and exhibited one-seventh of the alkaline p-nitrophenylphosphatase activity in the hepatic enzyme preparation contains of the alkaline pyrophosphatase activity. 3. The highly purified enzyme was a sialic-acid containing glycoprotein. 4. Sialidase-treated hepatic enzyme clearly presented the phenomenon of delayed mobility, and the delayed enzyme fraction stained more strongly than that of non-treated hepatic alkaline phosphatase. 5. In order to investigate the role of the carbohydrate region(s) of the hepatic alkaline phosphatase molecule on substrate binding, the effect of sialidase treatment on the rate of substrate inhibition of alkaline phosphatase was studied. In the case of hepatic enzyme without sialidase, substrate inhibition of alkaline phosphatase activity was clearly shown, while in the case of the hepatic enzyme with sialidase, there was hardly any substrate inhibition in the range of 1-8 mM p-nitrophenylphosphate.
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PMID:Partial purification and some properties of human liver alkaline phosphatase. 94 51

A subcellular fractionation method to isolate simultaneously apical and basolateral plasma membrane fractions from the human adenocarcinoma cell line Caco-2, grown on filter supports, is described. The method employs sucrose-density-gradient centrifugation and differential precipitation. The apical membrane fraction was enriched 14-fold in sucrase-isomaltase and 21-fold in 5'-nucleotidase compared with the homogenate. The basolateral membrane fraction was enriched 20-fold relative to the homogenate in K(+)-stimulated p-nitrophenylphosphatase. Alkaline phosphatase was enriched 15-fold in the apical membrane fraction and 3-fold in the basolateral membrane fraction. Analytical density-gradient centrifugation showed that this enzyme was a true constituent of both fractions, and experiments measuring alkaline phosphatase release following treatment with phosphatidylinositol-specific phospholipase C showed that in both membrane fractions the enzyme was glycosyl-phosphatidylinositol-linked. There was very little contamination of either membrane fraction by marker enzymes of the Golgi complex, mitochondria or lysosomes. Both membrane fractions were greater than 10-fold purified with respect to the endoplasmic reticulum marker enzyme alpha-glucosidase. Protein composition analysis of purified plasma membrane fractions together with domain-specific cell surface biotinylation experiments revealed the presence of both common and unique integral membrane proteins in each plasma membrane domain. The post-synthetic transport of endogenous integral plasma membrane proteins was examined using the devised subcellular fractionation procedure in conjunction with pulse-chase labelling experiments and immunoprecipitation. Five common integral membrane proteins immunoprecipitated by an antiserum raised against a detergent extract of the apical plasma membrane fraction were delivered with the same time course to each cell-surface domain.
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PMID:The post-synthetic sorting of endogenous membrane proteins examined by the simultaneous purification of apical and basolateral plasma membrane fractions from Caco-2 cells. 131 18

To investigate the functional stages of osteoclasts, the ultrastructural histochemical distribution of the lysosomal enzymes [acid phosphatase (tartrate-sensitive) and neutral phosphatase], the plasma membrane enzymes [alkaline phosphatase, Ca(++)-ATPase, and alkaline ouabain-insensitive p-nitrophenylphosphatase (alkaline p-NPPase)], and the mitochondrial enzyme (cytochrome C oxidase) was evaluated in the chicken tibial metaphysis. Both active-appearing and detached (resting) osteoclasts were studied. Serial sectioning was used to identify detached osteoclasts which were present in the perivascular space. The ultrastructure of detached osteoclasts was similar to that of active osteoclasts, except for the lack of a ruffled border and clear zone, and an altered distribution pattern of small vesicles. Small vesicles were uniformly distributed in the cytoplasm of resting osteoclasts, whereas they were concentrated beneath the ruffled border of active osteoclasts. Alkaline p-NPPase, a marker enzyme for the basal ruffled border, was also apparent on the membrane of small vesicles. However, the vesicles did not possess Ca(++)-ATPase, a marker enzyme for the apical plasma membrane. These findings support the concept that small vesicles serve as a membrane reservoir for the ruffled border membrane. Pre-osteoclasts contained abundant mitochondria and lysosomes, prominent Golgi complexes, moderately developed endoplasmic reticulum, and lacked small vesicles. Pre-osteoclasts appear to fuse with osteoclasts which are attached to the bone surface, but not with detached osteoclasts. The small vesicles, from which the ruffled border arises, are absent from pre-osteoclasts, suggesting that they develop after fusion with pre-existing osteoclasts or after attachment to the bone surface. Alkaline p-NPPase appears to be a marker for differentiation of pre-osteoclasts to mature osteoclasts.
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PMID:Characterization of the functional stages of osteoclasts by enzyme histochemistry and electron microscopy. 166 72

Thirty-three different flavonoids were screened for their ability to influence ATP-dependent Ca2+ uptake by rat liver plasma membrane vesicles. Nine of the flavonoids, at a concentration of 100 microM inhibited Ca2+ uptake by more than 20%. The remaining 24 flavonoids exhibited little or no effect. The relative order of potency of the more biologically active flavonoids was myricetin greater than butein greater than phloretin = luteolin greater than eriodictyol = silybin. Myricitrin and phloridzin, the glycosides of myricetin and phloretin, respectively, had no effect. The degree of inhibition caused by myricetin was concentration dependent and was also affected by the preincubation time. After 10 min of preincubation, 52 microM myricetin lowered the initial rate of 45Ca uptake by 50%. The inhibition by myricetin was non-competitive with respect to Mg-ATP and of a mixed type with respect to Ca2+. At a concentration of 100 microM, myricetin had no effect on several plasma membrane enzymes such as 5'-nucleotidase, alkaline phosphatase and a Ca2(+)-activated ATPase but inhibited K(+)-dependent p-nitrophenyl phosphatase by 83%. The ATP-dependent Ca2+ transport systems located on the plasma membrane or endoplasmic reticulum derived from other tissues were also inhibited by myricetin. Analysis of the structure-activity relationship revealed that lipid solubility and polyhydroxylation particularly at positions 5,7,3' and 4' of the flavonoid ring structure enhanced the ability of the flavonoid to inhibit Ca2+ uptake. The results suggest that inhibition of Ca2+ transport activity probably involves the interaction of the phenolic groups of the flavonoid with the Ca2+ transporting protein.
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PMID:Effect of myricetin and other flavonoids on the liver plasma membrane Ca2+ pump. Kinetics and structure-function relationships. 199 24

A soluble form of an alkaline phosphatase obtained from rat osseous plates was purified 204-fold with a yield of 24.3%. The purified enzyme showed a single protein band of Mr 80,000 on SDS-PAGE and an apparent molecular weight of 163,000 by gel filtration on Sephacryl S-300 suggesting a dimeric structure for the soluble enzyme. The specific activity of the enzyme at pH 9.4 in the presence of 2 mM MgCl2 was 19,027 U/mg and the hydrolysis of p-nitrophenyl phosphate (K0.5 = 92 microM) showed positive cooperativity (n = 1.5). The purified enzyme showed a broad substrate specificity, however, ATP, bis(p-nitrophenyl) phosphate and pyrophosphate were among the less hydrolyzed substrates assayed. Surprisingly the enzyme was not stimulated by cobalt and manganese ions, in contrast with a 20-25% stimulation observed for magnesium and calcium ions. Zinc ions exerted a strong inhibition on p-nitrophenylphosphatase activity of the enzyme. This paper provides a simple experimental procedure for the isolation of a soluble form of alkaline phosphatase which is induced by demineralized bone matrix during endochondral ossification.
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PMID:Alkaline phosphatase from rat osseous plates: purification and biochemical characterization of a soluble form. 206 78

1. Matrix-induced alkaline phosphatase prepared from rat osseous plate was solubilized with polidocanol and purified on a Sephacryl S-300 column. 2. Purified solubilized alkaline phosphatase has a molecular weight of ca 115,000 and bind one magnesium and two zinc ions. At least 110 detergent molecules are bound to each enzyme molecule. 3. Solubilization and purification procedures did not destroy the ability of the enzyme to hydrolyze adenosine-5'-triphosphate, p-nitrophenylphosphate, pyrophosphate and bis p-nitrophenylphosphate. 4. Magnesium, manganese and cobalt ions are stimulators of PNPPase activity of solubilized enzyme whereas calcium and zinc ions are inhibitors.
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PMID:Solubilization of membrane-bound matrix-induced alkaline phosphatase with polyoxyethylene 9-lauryl ether (polidocanol): purification and metalloenzyme properties. 215 26

A comparative characteristic of alkaline phosphatase and Na(+)-K(+)-ATPase localization activity within white rat myocardium is presented at the ultrastructural level. Both different in principle and common features of the enzyme reactional products precipitation are revealed. The original technique is used to determine ouabain-sensitive potassium-dependent p-nitrophenylphosphatase part of Na(+)-K(+)-ATPase complex at physiological pH. The verification of the main characteristics of Na(+)-K(+)-ATPase complex membrane localization activity within the rat myocardium using this cytochemical procedure are discussed.
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PMID:[The comparative characteristics of the localization of the activity of alkaline phosphatase and ouabain-sensitive, potassium-dependent p-nitrophenyl phosphatase in the myocardium of white rats at the ultrastructural level]. 216 77

Small cultures of human amniotic cells were preincubated for 24 h. Human prolactin was then added to the medium. After a further short period of incubation the tubes were chilled, the medium removed and the cells rinsed with saline. The tubes then received cold Tris-sucrose and were frozen, to disrupt the cells. After thawing, adenosine triphosphatase (ATPase) and p-nitrophenyl phosphatase (PNPase) were measured. Buffer was added containing either ATP or PNP and the tubes were incubated for 30 min. Inorganic phosphate released from ATP and p-nitrophenol was measured spectrophotometrically. Prolactin stimulated both enzyme activities. The ATPase log dose-response curve was linear between approximately 12.5 and 200 mIU/l. It was inhibited by ouabain. Isobutyl-1-methylxanthine inhibited the ATPase but not the alkaline phosphatase activity. One of these human amniotic cell enzymes may provide the basis for a sensitive bioassay for human prolactin.
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PMID:Enzyme activation of human prolactin: a potential basis for a bioassay. 247 90

A partially purified bovine cortical bone acid phosphatase, which shared similar characteristics with a class of acid phosphatase known as tartrate-resistant acid phosphatase, was found to dephosphorylate phosphotyrosine and phosphotyrosyl proteins, with little activity toward other phosphoamino acids or phosphoseryl histones. The pH optimum was about 5.5 with p-nitrophenyl phosphate as substrate but was about 6.0 with phosphotyrosine and about 7.0 with phosphotyrosyl histones. The apparent Km values for phosphotyrosyl histones (at pH 7.0) and phosphotyrosine (at pH 5.5) were about 300 nM phosphate group and 0.6 mM, respectively, The p-nitrophenyl phosphatase, phosphotyrosine phosphatase, and phosphotyrosyl protein phosphatase activities appear to be a single protein since these activities could not be separated by Sephacryl S-200, CM-Sepharose, or cellulose phosphate chromatographies, he ratio of these activities remained relatively constant throughout the purification procedure, each of these activities exhibited similar thermal stabilities and similar sensitivities to various effectors, and phosphotyrosine and p-nitrophenyl phosphate appeared to be alternative substrates for the acid phosphatase. Skeletal alkaline phosphatase was also capable of dephosphorylating phosphotyrosyl histones at pH 7.0, but the activity of that enzyme was about 20 times greater at pH 9.0 than at pH 7.0. Furthermore, the affinity of skeletal alkaline phosphatase for phosphotyrosyl proteins was low (estimated to be 0.2-0.4 mM), and its protein phosphatase activity was not specific for phosphotyrosyl proteins, since it also dephosphorylated phosphoseryl histones. In summary, these data suggested that skeletal acid phosphatase, rather than skeletal alkaline phosphatase, may act as phosphotyrosyl protein phosphatase under physiologically relevant conditions.
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PMID:Phosphotyrosyl-specific protein phosphatase activity of a bovine skeletal acid phosphatase isoenzyme. Comparison with the phosphotyrosyl protein phosphatase activity of skeletal alkaline phosphatase. 258 Aug 26


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