Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

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

Nucleoside triphosphate pyrophosphohydrolase (EC 3.6.1.8) activity is associated with matrix vesicles purified from collagenase digests of fetal calf epiphyseal cartilage. This enzyme hydrolyzes nucleoside triphosphates to nucleotides and PPi, the latter inducing precipitation in the presence of Ca2+ and Pi. An assay for matrix vesicle nucleoside triphosphate pyrophosphohydrolase is developed using beta, gamma-methylene ATP as substrate. The assay is effective in the presence of matrix vesicle-associated ATPase, pyrophosphatase, and alkaline phosphatase activities. A soluble nucleoside triphosphate pyrophosphohydrolase is obtained from matrix vesicles by treatment with 5 mM sodium deoxycholate. The solubilized enzyme induced the precipitation of calcium phosphate in the presence of ATP, Ca2+, and Pi. Extraction of deoxycholate-solubilized enzymes from matrix vesicles with 1-butanol destroys nucleoside triphosphate pyrophosphohydrolase activity while enhancing the specific activities of ATPase, pyrophosphatase, and alkaline phosphatase. In solutions devoid of ATP and matrix vesicles, concentrations of PPi between 10 and 100 microM induce calcification in mixtures containing initial Ca2+ X P ion products of 3.5 to 7.9 mM2. This finding plus the discovery of nucleoside triphosphate pyrophosphohydrolase in matrix vesicles supports the view that these extracellular organelles induce calcium precipitation by the enzymatic production of PPi. Nucleoside triphosphate pyrophosphohydrolase is more active against pyrimidine nucleoside triphosphates than the corresponding purine derivatives. The pH optimum is 10.0 and the enzyme is neither activated nor inhibited by Mg2+ or Ca2+ ions or mixtures of the two. Vmax at pH 7.5 for beta, gamma-methylene ATP is 0.012 mumol of substrate hydrolyzed per min per mg of protein and Km is below 10 microM. The enzyme is irreversibly destroyed at pH 4 and is stable at pH 10.5.
...
PMID:The role of nucleoside triphosphate pyrophosphohydrolase in in vitro nucleoside triphosphate-dependent matrix vesicle calcification. 613 31

Pyrophosphate, p-nitrophenyl phosphate and a variety of pyrimidine and purine nucleotides are hydrolyzed by the solubilized membrane-bound enzymes of the brush border plasma membrane of Hymenolepis diminuta. The pH optima (or ranges) for hydrolysis of substrates are 8.0 (pyrophosphate), 8.8 (p-nitrophenyl phosphate), 8.4-8.9 (nucleoside monophosphates), and 7.1-8.1 (nucleoside triphosphates); all substrates, with the exception of nucleoside triphosphates, have a higher affinity for the solubilized enzyme at pH 7.4 than at their optimal pH for hydrolysis. ATP is degraded completely by the enzyme preparation to adenosine and inorganic phosphate, but since neither ADP nor ATP accumulate in the incubation medium it is not known whether ATP hydrolysis involves the sequential hydrolysis of terminal phosphate groups. Isoelectric focusing and various chromatographic procedures (gel permeation, ion-exchange and hydrophobic interaction chromatography) fail to separate the alkaline phosphatase, phosphodiesterase, 5'-nucleotidase, adenosine triphosphatase and ribonuclease activities associated with the solubilized membrane preparation. Additionally, inhibitor studies indicate that only a single enzyme with low substrate specificity is involved in the hydrolysis of nucleotides, p-nitrophenyl phosphate, pyrophosphate and hexose phosphate esters. Purines and pyrimidines and their nucleosides interact with the active site, and in some instances activity of the enzyme is stimulated by an unknown mechanism.
...
PMID:Nucleotide hydrolysis by solubilized membrane-bound enzymes of the brush border plasma membrane of Hymenolepis diminuta. 613 88

The products derived from the degradation of the sixteen possible diribonucleoside monophosphates (NpN') by Fusarium phosphodiesterase-phosphomonoesterase were analyzed by means of thin layer chromatography. The analysis showed that NpN' was first cleaved into nucleoside N and 5'-nucleotide pN', which was then dephosphorylated to yield nucleoside N'. The dephosphorylation was fast when N' was adenosine or cytidine but slow when N' was guanosine or uridine. The cleavage reaction was followed by measuring the increase of absorbance due to hyperchromicity, and the kinetic constants, Km and kcat, were determined for the sixteen dinucleoside phosphates. The Km value was higher, for a given N, when N' was a pyrimidine nucleoside than when N' was a purine nucleoside. For a given N', uridine as N gave the highest Km value and adenosine gave the lowest one. The kcat value was the highest, for a given N, when N' was cytidine. For a given N', uridine as N gave by far the lowest kcat value. These results can be interpreted in terms of two binding sites on the enzyme with different base preferences. Comparison of kcat/Km values suggested that the base of nucleoside N plays an important role in determining whether a dinucleoside phosphate is a good substrate of the enzyme. The dinucleoside phosphates with uridine as N were found to be particularly poor substrates of the enzyme.
...
PMID:Mode of hydrolysis of diribonucleoside monophosphates by phosphodiesterase-phosphomonoesterase of Fusarium moniliforme. 627 68

Endonuclease V of bacteriophage T4 has been purified to physical homogeneity from T4D-infected Escherichia coli 1100. The enzyme, whose molecular weight is 16,000, possessed two distinct catalytic activities, a pyrimidine dimer-DNA glycosylase and an apurinic/apyrimidinic endonuclease. They acted on UV-irradiated poly(dA) . poly(dT) in a sequential manner; the glycosylase cleaved the N-glycosyl bond between the 5'-pyrimidine of a dimer and the corresponding sugar and then the endonuclease hydrolyzed a phosphodiester bond on the 3'-side of the apyrimidinic site. The 5'-termini thus generated were phosphorylated by T4 polynucleotide kinase only after they had been subjected to direct photoreversal and then treated with alkaline phosphatase. By using two phage mutants, uvs-5 and uvs-13, it was shown that occurrence of an amber mutation in the denV gene caused a simultaneous loss of the two activities. Suppression of the mutation of uvs-5 rendered both activities partially active. When the mutation of uvs-13 was suppressed, a mutant form of enzyme that possessed only a glycosylase activity was produced. This suggests that there are two distinct domains in a single enzyme, each of which corresponds to one of the activities.
...
PMID:Purification and characterization of normal and mutant forms of T4 endonuclease V. 627 6

Pyrimidine nucleosides in blood plasma of rats were identified by different procedures, including chemical peak shift methods, before their quantification by reversed-phase high-performance liquid chromatography. The concentrations of uridine, cytidine, and deoxycytidine were 1.0 +/- 0.2, 10.6 +/- 1.9, and 33.4 +/- 5.4 mumol/l, respectively. Six hours after the administration of D-galactosamine, the level of circulating cytidine was severely depressed to 25% of control values; uridine decreased to 54% while deoxycytidine remained unchanged. 24 h after the dose of the amino sugar, the levels of cytidine and uridine returned to control values in blood plasma. Total acid-soluble uridine, cytidine, guanosine, and adenosine was determined by reversed-phase HPLC after treatment of the neutralized acid-soluble supernatant of freeze-clamped rat livers with phosphodiesterase and alkaline phosphatase. Six hours after its administration, D-galactosamine induced a 2.2-fold and a 1.6-fold rise in total acid-soluble uridine and cytidine, respectively. Co-administration of N-(phosphonoacetyl)-L-aspartate, an inhibitor of de novo pyrimidine synthesis, suppressed the increase in total acid-soluble uridine observed after D-galactosamine alone, but was without effect on the enhancement of total cytidine. Three hours after D-galactosamine and 15 min after [2-14C] cytidine, there was a rapid fall of the labeled nucleoside in blood plasma to 49% of control animals accompanied by a 2.8-fold rise in the total radioactivity of rat liver homogenates. From these results it can be concluded that the hepatocellular rise in total acid-soluble cytidine after D-galactosamine, in contrast to the increase in total acid-soluble uridine, originates from the phosphorylation of blood plasma cytidine via the salvage pathway. The depletion of circulating cytidine in the presence of hepatocellular UTP deficiency points to the importance of the liver and the hepatic UTP level for the clearance of blood plasma cytidine.
...
PMID:Depletion of blood plasma cytidine due to increased hepatocellular salvage in D-galactosamine-treated rats. 673 1

The major aminofluorene-DNA derivative formed from the carcinogen N-acetyl-2-aminofluorene in vivo in rat liver is N-(deoxyguanosin-8-yl)-2-aminofluorene. This nucleoside is hydrolyzed in aqueous solution at alkaline pH through the 7-8 guanine bond to form two pyrimidine derivatives which were separated by Sephadex LH-20 column chromatography and thin-layer chromatography on silica. From chemical, u.v., i.r., n.m.r. and mass spectral analysis the pyrimidine derivatives have been identified as 1-[6-(2,5-diamino-4-oxopyrimidinyl-N6-deoxyriboside)]-3-(2-fluorenyl)ureas, which probably are stereoisomers. Similar products were isolated from enzymatic hydrolysates of DNA reacted with N-hydroxy-2-aminofluorene under mildly acidic conditions (pH 5) and subsequent treatment with 0.1 N NaOH. Kinetic studies of the hydrolysis reaction showed that it occurs already at a measurable rate at pH 9.5 and 37 degrees C. The reaction is catalyzed by Mg2+ and Mn2+ ions and by alkaline phosphatase from E. coli.
...
PMID:Structural identification of the pyrimidine derivatives formed from N-(deoxyguanosin-8-yl)-2-aminofluorene in aqueous solution at alkaline pH. 727 79

The major 2-fluorenylamine-DNA derivative formed in vivo in rat liver after application of N-2-flourencylacetamide is N-(deoxyguanosin-8-yl)-2-fluorenylamine. This nucleoside, hydrolyzed under mild alkaline conditions with the opening of the imidazole ring, formed two pyrimidine derivatives which can be separated by Sephadex LH-20 column chromatography and thin-layer chromatography on silica. The hydrolysis reaction was catalyzed by metal ions and alkaline phosphatase from Escherichia coli.
...
PMID:Formation of N-2-fluorenylhydroxylamine adducts of DNA in vivo and in vitro and some of their properties. 734 70

Antibodies against the holo ecto-adenosinetriphosphatase (ATPase) of rat liver and antibodies against COOH-terminal peptides of the long isoform of this enzyme reacted in Western blots with a 105-kDa band from small intestinal brush-border membranes. Indirect immunofluorescence revealed reactive proteins predominantly at the apical surface of enterocytes with some staining of basolateral membranes and of vascular endothelium. Similar results were obtained with monoclonal antibodies against HA4, a protein from rat liver closely related to the ecto-ATPase. Since these results suggested the presence of an ecto-ATPase, ATP hydrolysis was studied in intact, right-side-out brush-border membrane vesicles. Nearly half of ATP hydrolysis was caused by alkaline phosphatase (AP). Besides purine and pyrimidine trinucleotides, AP also hydrolyzed ADP, AMP, pyrophosphate, and 4-nitrophenylphosphate. Inactivation of AP by cleavage of its membrane anchor and by removal of the Zn2+ necessary for its function left the ecto-ATPase that was activated by Ca2+ and Mg2+ and hydrolyzed purine and pyrimidine trinucleotides and dinucleotides, but not AMP, pyrophosphate, and 4-nitrophenylphosphate. These features are characteristic of an ATP diphosphohydrolase (EC 3.6.1.5, also called apyrase). The physiological role of the small intestinal ecto-ATPase may be the degradation of nutrient nucleotides.
...
PMID:Ecto-adenosinetriphosphatase in rat small intestinal brush-border membranes. 773 91

The control of hybridoma cell cultures in bioreactors requires the use of convenient indicators to monitor the proliferation of the biomass. In order to select appropriate indications, we followed the variations of several compounds including tumoral markers, polyamines, sialic acids, purine and pyrimidine bases, enzymes and metabolites such as glucose, lactate and amino acids, and the variations of cell density during batch culture. Significant correlations were found between the number of viable cells and alkaline phosphatase, beta-glucuronidase, glucose and lactate measured in the culture medium of hybridoma strains. The correlation calculated from alkaline phosphatase and beta-glucuronidase concentrations in culture medium underestimated cell number. The correlation established with glucose and lactate gave the best indication of cell proliferation in continuous culture with an immobilized cell bioreactor. Finally, the exact quantification of the biomass in these culture conditions can be obtained using the mean of glucose and lactate correlations.
...
PMID:Search for cell proliferation markers suitable for cell count in continuous immobilized cell bioreactors. 776 99

To evaluate the clinical utility of recently developed biochemical markers of bone turnover to monitor the response of osteoporotic patients to antiresorptive therapy, we compared the results of three advanced assays for markers of bone resorption and four of bone formation to high pressure liquid chromatography (HPLC)-fluorometric assays for urinary pyridinoline and deoxypyridinoline. These assays were also used to resolve the uncertainties concerning the rate of bone turnover in late postmenopausal (late-PMP) osteoporotic women. The rate of bone turnover in 85 women (mean +/- SD age, 63 +/- 6 yr) with low bone mass and all more than 5 yr postmenopausal (mean +/- SD yr PMP, 16 +/- 7 yr) was compared to that in 46 premenopausal women (mean +/- SD age, 40 +/- 5 yr) randomly selected from a large cohort and all having a normal spine bone mineral density (BMD). The late-PMP osteoporotic patients were a subset of patients enrolled in a double blind, placebo-controlled, randomized study comparing the effects of several doses of oral alendronate, a potent and specific inhibitor of bone resorption. Periodically during the 2-yr study, the women's spinal BMD and the level of several markers of bone turnover were measured. Serum total and intact osteocalcin, bone-specific alkaline phosphatase, and carboxy-terminal propeptide of type I collagen measured by RIA were used to assess bone formation. To assess bone resorption, we measured the urinary excretion of total pyridinoline (HPLC Pyr) and deoxypyridinoline (HPLC D-Pyr) by HPLC, type I collagen cross-linked N-telopeptide and urinary free PYR (F-Pyr) by enzyme-linked immunosorbent assay, and the serum concentration of type I collagen cross-linked C-telopeptide (ICTP) by RIA. All bone formation markers, except carboxy-terminal propeptide of type I collagen, and all bone resorption markers, except ICTP, were significantly increased above normal (33-171%; P < 0.001) in late-PMP osteoporotic women. The long term within-patient variability assessed over a 15-month period in the placebo group was low and was somewhat lower for serum markers (12.5-17.4%) than for urinary markers (24-29%). Under treatment with alendronate, resorption markers decreased earlier than markers of bone formation, consistent with a direct action of the drug to inhibit osteoclastic bone resorption. With the exception of F-Pyr and ICTP, the levels of bone markers were reduced to the normal premenopausal range, and this steady state was maintained from 6-15 months.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Comparison of new biochemical markers of bone turnover in late postmenopausal osteoporotic women in response to alendronate treatment. 798 77


<< Previous 1 2 3 4 5 Next >>

---