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

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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)

Human placental microsomal 5'-nucleotidase (EC 3.1.3.5) was prepared free of alkaline phosphatase by isoelectric focusing. A total of seven electrophoretic variants were isolated during the preparation of six placentas. Only three to six variants were found in a single placenta. The isoelectric pH's were 6.70, 6.44, 6.23, 6.02, 5.76, 5.63 and 5.44. These were found to be composed of variable quantities of a large, medium and low molecular weight form. The apparent molecular weights of the medium and light form of the enzyme were 86 500 and 43 500, respectively, as estimated from Stokes radius and sedimentation velocity determinations. The electrophoretic variants were not distinguishable with respect to specific activity and Michaelis constants for AMP, GMP or CMP or inhibition by ATP, CTP or adenosine. These electrophoretic variants appeared to be pseudoisozymes based upon different states of aggregation of a common primary sequence. There was a wide range of substrate specificity among nucleoside 5'-monophosphates which included 2-deoxyribose compounds. With AMP as 100, substrate activity was: CMP, 122; NMN, 74; GMP, 68: IMP, 63; XMP, 28 and UDP-glucose, 68. The Michaelis constants for AMP, GMP and CMP ranged from 12-18 muM, from 33-67 muM and from 170-250 muM, respectively. Although 5'-nucleotidase was active in the absence of divalent cation, 5 mM MgCl2 stimulated the enzyme activity to 234% of control and shifted the pH optimum of 9.8 to a plateau from pH 7.4-9.8.
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PMID:Purine catabolism in man: characterization of placental microsomal 5'-nucleotidase. 0 35

The translation of rabbit globin mRNA in cell-free systems derived from either wheat germ or rabbit reticulocyte was studied in the presence of various analogues of the methylated 5' terminus (cap) as a function of ionic strength. Inhibition by these analogues was strongly enhanced by increasing concentrations of KCl, K(OAc), Na(OAc), or NH4(OAc). At appropriate concentrations of K(OAc), both cell-free systems were equally sensitive to inhibition by m7GTP. At 50 mM K(OAc), the reticulocyte system was not sensitive to m7GMP or m7GTP, but at higher concentrations up to 200 mM K(OAc), both nucleotides caused strong inhibition. The compound in m7G5'ppp5'Am was inhibitory at all concentrations of K(OAc) ranging from 50 to 200 mM, although more strongly so at the higher concentrations. Over the same range of nucleotide concentrations, the compounds GMP, GTP, and G5'ppp5'Am were not inhibitors. The mobility on sodium dodecyl sulfate-polyacrylamide electrophoresis of the translation product was that of globin at all K(OAc) concentrations in the presence of m7GTP. Globin mRNA from which the terminal m7GTP group had been removed by chemical treatment (periodate-cyclohexylamine-alkaline phosphatase) or enzymatic treatment (tobacco acid pyrophosphatase-alkaline phosphatase) was translated less efficiently than untreated globin mRNA at higher K(OAc) concentrations, but retained appreciable activity at low K(OAc) concentrations.
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PMID:Translational recognition of the 5'-terminal 7-methylguanosine of globin messenger RNA as a function of ionic strength. 20 16

Incubation of purified rat brain tubulin with guanosine 5'-methylene diphosphonate [GMP(CH2)P] (1 mM), a GDP analog resistant to hydrolysis, results in the polymerization of 20-30% of the total tubulin present. Analogous incubations with GDP (1 mM) do not result in tubulin polymerization. Polymerization with GMP(CH2)P occurs in the presence of alkaline phosphatase (EC 3.1.3.1) under conditions that completely hydrolyze the likely phosphate donors (GTP, GDP, and GMP) as well as the potential product [GMP(CH2)PP] of the transphosphorylase activity present in purified tubulin preparations. Tubulin polymerization in vitro thus can occur in the absence of gamma-phosphate and phosphate bond hydrolysis at the exchangeable nucleotide-binding site of tubulin. Polymerization of tubulin by GMP(CH2)P is neither prevented nor reversed by concentrations of calcium (2 mM) that prevent microtubule assembly and disrupt already formed microtubules induced by GTP. However, tubulin polymerized with GMP(CH2)P is readily depolymerized by cold (4 degrees, 30 min). The possible involvement of GTP alpha-beta bond hydrolysis must be considered seriously as playing a role in the process of microtubule depolymerization.
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PMID:Role of nucleotides in tubulin polymerization: effect of guanosine 5'-methylene diphosphonate. 27 19

In microsomes obtained from mouse pancreatic islets, the Mg complex of adenosine 5'-triphosphate (MgATP) increased the dissociation constant (KD) for binding of [3H]glibenclamide by sixfold. In the presence of Mg2+, not only ATP but also adenosine 5'-0-(3-thiotriphosphate) (ATP gamma S), adenosine 5'-diphosphate (ADP), guanosine 5'-triphosphate (GTP), guanosine 5'-diphosphate (GDP), guanosine 5'-0-(3-thiotriphosphate) (GTP gamma S) and guanosine 5'-0-(2-thiodiphosphate) (GDP beta S) inhibited binding of [3H]glibenclamide. These effects were not observed in the absence of Mg2+. Half maximally effective concentrations of the Mg complexes of ATP, ADP, ATP gamma S and GDP were 11.6, 19.0, 62.3 and 90.1 mumol/l, respectively. The non-hydrolyzable analogues adenosine 5'-(beta,gamma-imidotriphosphate) (AMP-PNP) and guanosine 5'-(beta,gamma-imidotriphosphate) (GMP-PNP) did not alter [3H]glibenclamide binding in the presence of Mg2+, MgADP acted much more slowly than MgATP and both MgADP and MgGDP did not inhibit [3H]glibenclamide binding when the concentrations of MgATP and MgGTP were kept low by the hexokinase reaction. Development of MgATP-induced inhibition of [3H]glibenclamide binding and dissociation of [3H]glibenclamide binding occurred at similar rates. However, the reversal of MgATP-induced inhibition of [3H]glibenclamide binding was slower than the association of [3H]glibenclamide with its binding site. Exogenous alkaline phosphatase accelerated the reversal of MgATP-induced inhibition of [3H]glibenclamide binding. MgATP enhanced displacement of [3H]glibenclamide binding by diazoxide. The data suggest that sulfonylureas and diazoxide exert their effects by interaction with the same binding site at the sulfonylurea receptor and that protein phosphorylation modulates the affinity of the receptor.
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PMID:Phosphate and thiophosphate group donating adenine and guanine nucleotides inhibit glibenclamide binding to membranes from pancreatic islets. 190 88

Brucellae are facultative intracellular bacterial pathogens that reside primarily in cells of the reticuloendothelial system. The high-speed supernatant obtained after centrifuging a suspension of Brucella abortus that had been frozen-thawed and sonicated contained abundant phosphomonoesterase activity, determined by using 4-methylumbelliferylphosphate as the substrate; this enzyme was purified 2,900-fold (yield, 570%) by chromatography on DE-52 cellulose and hydroxylapatite columns and high-performance liquid chromatography-gel filtration. The native enzyme had a molecular mass of 120,000 daltons (+/- 10,000 daltons), as determined by gel filtration chromatography, and resolved into two bands (60,000 and 66,000 daltons) when subjected to polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The B. abortus phosphomonoesterase had the following properties: pH optimum, 6.0 to 6.5; isoelectric point, 3.0; substrate specificity, 5'-AMP greater than 3'-AMP greater than 3'-GMP greater than 5'-GDP greater than 5'-CDP greater than 5'-CTP greater than 5'-UPT greater than phosphotyrosine greater than phosphoserine greater than phosphothreonine. The Km for 5'-AMP was 0.37 mM. Phosphatidylinositol 4,5-bisphosphate and myo-inositol 1,3,4-trisphosphate were poor substrates for the B. abortus enzyme. The phosphomonoesterase did not inhibit superoxide anion production by human neutrophils stimulated with formyl-methionyl-leucyl-phenylalanine. The phosphomonoesterase may be one of the bacterial enzymes in the pathway leading to the production of adenine, which is secreted by B. abortus and blocks the activation of neutrophils.
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PMID:Characterization of a phosphomonoesterase from Brucella abortus. 215 65

The molybdenum cofactor of formylmethanofuran dehydrogenase from methanol-grown Methanosarcina barkeri was isolated as the [di(carboxamidomethyl)]-derivative. The alkylated factor showed an absorption spectrum and chemical properties identical to those recently reported for the molybdenum cofactor of dimethyl sulfoxide reductase from Rhodobacter sphaeroides. By treatment with nucleotide pyrophosphatase the factor was resolved into two components, which were identified as [di(carboxamidomethyl)]-molybdopterin and GMP by their absorption spectra, their retention times on Lichrospher RP-18, and by their conversion to dephospho-[di(carboxamidomethyl)]-molybdopterin and guanosine, respectively, in the presence of alkaline phosphatase. The GMP-moiety was sensitive to periodate, identifying it as the 5'-isomer. These results demonstrate that the molybdenum cofactor isolated from formylmethanofuran dehydrogenase contains the phosphoric anhydride of molybdopterin and 5'-GMP.
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PMID:The molybdenum cofactor of formylmethanofuran dehydrogenase from Methanosarcina barkeri is a molybdopterin guanine dinucleotide. 225 82

The nature of molybdenum cofactor in the bacterial enzyme dimethyl sulfoxide reductase has been investigated by application of alkylation conditions that convert the molybdenum cofactor in chicken liver sulfite oxidase and milk xanthine oxidase to the stable, well-characterized derivative [di(carboxamidomethyl)]molybdopterin. The alkylated pterin obtained from dimethyl sulfoxide reductase was shown to be a modified form of alkylated molybdopterin with increased absorption in the 250-nm region of the spectrum and altered chromatographic behavior. The complex alkylated pterin was resolved into two components by treatment with nucleotide pyrophosphatase. These were identified as di(carboxamidomethyl)molybdopterin and GMP by their absorption spectra, coelution with standard compounds, and by further degradation by alkaline phosphatase to dephospho [di(carboxamidomethyl)]molybdopterin and guanosine. The GMP moiety was sensitive to periodate, identifying it as the 5' isomer. Chemical analysis of the intact alkylated pterin showed the presence of two phosphate residues per pterin. These results established that the pterin isolated from dimethyl sulfoxide reductase contains the phosphoric anhydride of molybdopterin and 5'-GMP, which is designated molybdopterin guanine dinucleotide.
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PMID:Molybdopterin guanine dinucleotide: a modified form of molybdopterin identified in the molybdenum cofactor of dimethyl sulfoxide reductase from Rhodobacter sphaeroides forma specialis denitrificans. 232 78

Incorporation of 32P from [gamma-32P]ATP into phosphatidylinositol 4,5-bisphosphate (PIP2) in membranes isolated from rat brain was enhanced in a concentration-dependent manner by the GTP analogue guanosine 5'-O-(thio)triphosphate (GTP gamma S). In contrast, neither the labeling of phosphatidylinositol 4-phosphate in the same membranes nor PIP kinase activity in the soluble fraction were stimulated by GTP gamma S. Synthesis of [32P]PIP2 was not stimulated by GTP, GDP, GMP, or ATP; however, the stimulatory effects of GTP gamma S were antagonized by GTP, GDP, and guanosine 5'-O-thiodiphosphate (GDP beta S). The nucleotide-stimulated labeling of PIP2 was not due to protection of [gamma-32P] ATP from hydrolysis, activation of PIP2 hydrolysis by phospholipase C, or inhibition of PIP2 hydrolysis by its phosphomonoesterase. Therefore, phosphatidylinositol 4-phosphate kinase activity in brain membranes may be regulated by a guanine nucleotide regulatory protein. This system may enhance the resynthesis of PIP2 following receptor-mediated activation of phospholipase C.
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PMID:Regulation of brain phosphatidylinositol-4-phosphate kinase by GTP analogues. A potential role for guanine nucleotide regulatory proteins. 253 38

When electrophoresed on an agarose gel, the DNA isolated from neocarzinostatin- (NCS-) treated HeLa cells migrates in a ladder of discrete bands indicative of preferential breakage in the linker region of the nucleosomes. The 5'-termini of the drug-induced DNA strand breaks were characterized by reduction of the nucleoside 5'-aldehyde ends to 5'-hydroxyls followed by incorporation of 32P from [gamma-32P]ATP by polynucleotide kinase and treatment of the DNA with hot alkali and alkaline phosphatase prior to the kinase assay to give the total 5'-termini. In DNA isolated from NCS-treated cells, nucleoside aldehyde accounts for 30-45% of the drug-generated 5' ends; the remainder have PO4 termini. By contrast, 5'-terminal nucleoside aldehyde in DNA cut with the drug in vitro exceeds 80% of the total 5' ends. Of the 32P representing nucleoside aldehyde in DNA from NCS-exposed cells, 77% is in TMP; the rest is in AMP much greater than CMP greater than GMP, a distribution in excellent agreement with that obtained for in vitro drug-treated DNA. DNA sequencing experiments, using the 340 base pair alphoid DNA fragment isolated from drug-treated cells, show that the pattern of breakage produced by NCS within a defined sequence of DNA in intact cells is similar to that in the in vitro reaction, with a preferential attack at thymidylate residues, but a much higher concentration of the drug was required to cause comparable breakage in intact cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mechanism and base specificity of DNA Breakage in intact cells by neocarzinostatin. 295 Sep 23

Reaction of N-hydroxy-2-aminofluorene (N-OH-AF) with rRNA at pH 5.0 decreased the molecular weight of the polynucleotide. Toluene-soluble aryl derivatives were released on hydrolysis of fluorenylamine- and biphenylamine-substituted RNA by treatment with venom phosphodiesterase and alkaline phosphatase. These data suggested that arylhydroxylamines, activated by incubation at pH 5.0 or by enzymatic O-acetylation, might react with the phosphate group of RNA to give unstable phosphate triesters. Spontaneous hydrolysis of these triesters would result in cleavage of the polynucleotide chain. Further enzymatic hydrolysis of the phosphate esters would yield nonpolar arylamine derivatives. Enzymatically degraded 4-aminobiphenyl(ABP)-RNA adducts were examined by high performance liquid chromatography (HPLC) for the presence of a putative phosphorylated adduct. Synthetic standards of the C-8-guanosine monophosphate-ABP adduct (ABP-GMP) and o-aminobiphenyl-O-phosphate were used as markers in the analysis of the digested RNA. A phosphate adduct of ABP was undetectable by these methods. The data also indicated that the ABP-GMP formed in the acyltransferase-mediated binding of N-hydroxy-4-acetylaminobiphenyl (N-OH-AABP) to RNA is readily degraded during the enzymatic digestion of the RNA adduct.
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PMID:Arylhydroxylamine-induced ribonucleic acid chain cleavage and chromatographic analysis of arylamine-ribonucleic acid adducts. 616 6


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