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)

The synthesis of some substituted 7-hydroxy-5H-1,3,4-oxadiazolo [3,2-a]pyrimidin-5-ones, a class of bicyclics with unexplored pharmacotoxicological properties, is described. Reacting the 2-phenyl derivative with bis(2,4,5-trichlorophenyl)benzylmalonate afforded a linear pyrano-oxadiazolopyrimidinedione. The assigned structures were verified by IR, 1H-NMR, and mass spectral studies. Six compounds of the series were screened for in vitro antibacterial and antifungal activities. The effect of four compounds on alkaline phosphatase enzyme was also examined.
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PMID:Synthesis and biological investigations of some 5H-1,3,4-oxadiazolo[3,2-a]pyrimidin-5-ones. 706 40

Cadmium can replace zinc and magnesium in alkaline phosphatase from Escherichia coli, which permits the characterization of the catalytically important metal-binding sites by 113Cd NMR. At pH 6.5, in the absence of phosphate, two equivalents of cadmium are bound in identical sites (A), one in each monomer. Either raising the pH or phosphorylation of Cd2AP (AP is apoalkaline phosphatase) results in migration of Cd(II) from the site A in one monomer to the opposite monomer to occupy a second site (B) adjacent to the A site in the first monomer, a site stabilized by phosphorylation or high pH. At pH 6.5 in the presence of phosphate, the 113Cd NMR spectrum of Cd6AP consists of three narrow resonances from three pairs of fully occupied sites, A, B, and C. The resonances at 153 and 70 ppm represent two metal sites (A and B) 3.9 A apart at each active center and adjacent to the serine phosphorylated during turnover. At this pH the enzyme exists almost exclusively as the covalent phosphoseryl form E-P with a 31P resonance at approximately 9 ppm. As the pH is raised a 31P signal from the noncovalent E.P complex appears at approximately 13 ppm. This is reflected in the 113Cd spectrum by a split of both the A- and B-site resonances into pairs, a set at 137 and 65 ppm for E.P, and 153 and 70 ppm for the E-P species. 113Cd-O-31P coupling of 30 Hz on the 31P resonance of E.P shows the noncovalently bound phosphate to be coordinated to one but not both metal ions at each active site. The resonance of E-P is not coupled and thus the phosphoseryl residue appears to shift out of the coordination sphere of the active site metal ion.
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PMID:113Cd NMR of Cd(II)-substituted Zn(II) metalloenzymes. 714 Sep 97

Glycoproteins that contain phosphohexosyl groups were found to be present in the myelin- and synaptosomal-enriched fractions as well as in the microsomes of rat brain. The kinetics of flow of intraperitoneally injected [32P]phosphate suggests that the phosphate is enzymatically added in structures found in the microsomal fraction. The newly synthesized phosphoglycoproteins then appear in the soluble fraction of the synaptosomes and in the cytosol, prior to incorporation into the membranes of the synaptosomes and myelin. Phosphoglycopeptides recovered from the phosphoglycoprotein contain 3 Mannose units per N-acetylglucosamine residue; one of the mannose residues is phosphorylated. [13C]NMR studies indicate that the phosphoglycopeptides contain a chitobiose group and more than four sugar residues. Thus, the phosphomannoglycopeptides from rat brain contain an average of 2 N-acetylglucosamine, 6 mannose, and two phosphate moieties per oligosaccharide chain. Enzymatic treatment with alpha-mannosidase failed to remove the phosphomannose, although some mannose residues were released. Thus, the phosphorylated mannose is not removed by the glycosidase and terminal nonphosphorylated mannose residues are present in the oligosaccharide. The phosphate residues are removed by treatment with alkaline phosphatase.
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PMID:The metabolism and structure of phosphoglycoproteins in rat brain. 715 76

In prior studies, we examined the effects of the radioprotective and chemoprotective agent WR-2721 [S-2-(3-aminopropylamino)ethylphosphorothioic acid] on the in vivo biotransformation of the cisplatin [cis-diamminedichloroplatinum(II)] analog ormaplatin [(d,I)trans-1,2-diaminocyclohexanetetrachloroplatinum(IV), Pt(dach)Cl4, (formerly called tetraplatin)]. Those data suggested that a direct interaction between WR-2721 and ormaplatin and/or the corresponding Pt(II) drug, Pt(dach)Cl2, may be occurring in vivo. This would be in contrast to the generally accepted hypothesis that WR-2721 is a prodrug that must first be converted by alkaline phosphatase to a free thiol compound, WR-1065, before any appreciable reactivity would be evident. However, the major biotransformation product observed in the peritoneal fluid, plasma, and all tissues was Pt(dach)(WR-1065). We report here on further investigations into the in vitro reactivity of Pt(dach) compounds with WR-2721 and WR-1065. Separation of reaction products resulting from incubation of Pt(dach)(malonato) with either WR-2721 or WR-1065 under physiological conditions gave profiles that were indistinguishable by reverse phase HPLC and cation exchange HPLC at two different pHs. 31P NMR characterization of the dephosphorylation of WR-2721 revealed essentially no loss of inorganic phosphate for up to 24 hr when incubated in unbuffered water at 30 degrees. In contrast, when incubated with a 1:1 molar ratio of cisplatin under the same conditions, the WR-2721 signal was decreased markedly in the first 5 min, and had disappeared almost completely by 1 hr. The signal corresponding to inorganic phosphate increased in parallel to the decrease in the WR-2721 signal. No intermediate formation of a complex containing both platinum and phosphate could be detected at any time. These data suggest that the reaction between WR-2721 and platinum complexes results in rapid dephosphorylation of WR-2721, and, consequently, that the reaction products formed with either WR-2721 or WR-1065 and Pt(II) complexes are identical.
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PMID:HPLC and 31P NMR characterization of the reaction between antitumor platinum agents and the phosphorothioate chemoprotective agent S-2-(3-aminopropylamino)ethylphosphorothioic acid (WR-2721). 750 92

The lipopolysaccharide of the recombinant strain Salmonella minnesota r595-207 expressing the genus-specific epitope of Chlamydia lipopolysaccharide [Holst, O., Brade, L., Kosma, P. and Brade, H. (1991) J. Bacteriol, 173, 1862-1866] was sequentially de-O- and de-N-acylated by mild hydrazinolysis and treatment with 4 M KOH, respectively. The resulting mixture of compounds was separated by high-performance anion-exchange chromatography and gel-permeation chromatography, yielding four oligosaccharide phosphates two of which were readily identified by their 1H-NMR- and 13C-NMR spectra as alpha-Kdo-(2-4)-alpha-Kdo-(2-6)-beta-D-GlcpN-(1-6)-alpha-D-Glcp N 1,4'-bisphosphate (tetrasaccharide bisphosphate; Kdo = 3-deoxy-D-manno-octulopyranosonic acid) and alpha-Kdo-(2-8)-alpha-Kdo-(2-4)-alpha-Kdo-(2-6)-beta-D-GlcpN-(1-6) -alpha-D- GlcpN 1,4'-bisphosphate (pentasaccharide bisphosphate) [Holst, O., Broer, W., Thomas-Oates, J.E., Mamat, U. and Brade, H. (1993) Eur. J. Biochem. 214, 703-710]. The structures of the other two compounds were established by chemical analysis, NMR spectroscopy, and fast-atom-bombardment mass spectrometry as alpha-Kdo- (2-4)-alpha-Kdo-(2-6)-beta-D-GlcpN-(1-6)-alpha-D-GlcpN 1-phosphate (tetrasaccharide 1-phosphate) and alpha-Kdo-(2-8)-alpha-Kdo-(2-4)-alpha-Kdo-(2-6)-beta-D-GlcpN-(1-6) -alpha-D- GlcpN 1-phosphate (pentasaccharide 1-phosphate). alpha-Kdo-(2-4)-alpha-Kdo-(2-6)-beta-D-GlcpN-(1-6)-alpha/beta- D-GlcpN 4'-phosphate (tetrasaccharide 4'-phosphate) and alpha-Kdo-(2-8)-alpha-Kdo-(2-4)-alpha-Kdo-(2-6)-beta-D-GlcpN-(1-6) -alpha/beta-D-GlcpN 4'-phosphate (pentasaccharide 4'-phosphate) were prepared from the 1,4'-bisphosphates isolated from the recombinant strain Escherichia coli F515-207 by treatment with alkaline phosphatase and purification by high-performance anion-exchange chromatography and gel-permeation chromatography. Their structures were characterised by chemical analysis, NMR spectroscopy, and fast-bombardment mass spectrometry.
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PMID:Preparation and structural analysis of oligosaccharide monophosphates obtained from the lipopolysaccharide of recombinant strains of Salmonella minnesota and Escherichia coli expressing the genus-specific epitope of Chlamydia lipopolysaccharide. 751 46

The hydrolysis and transphosphorylation reactions of a series of phosphate monoesters, ROPO3(2)-(R = 2,4-dinitrophenyl, 4-nitrophenyl, phenyl, glucose-1, glycerol-1, methyl, ethyl, and dodecyl), catalyzed by Escherichia coli alkaline phosphatase and a mutant enzyme, Ser102Cys, have been studied at alkaline pH using the rates of change in the 31P NMR signals of substrate, the hydrolysis product (inorganic phosphate), and the transphosphorylation product (O-Tris phosphate) as the assay. The kcat at pH 8.0 for the wild-type enzyme is approximately 30 s-1 and is independent of the nature of the R group, when the pKa of the leaving group is < 10. Under these conditions the rate of phosphorylation is much faster than dissociation of inorganic phosphate, 15-60 s-1. If the pKa of the leaving group is between 10 and 15, phosphorylation and dissociation of the product phosphate both contribute to the rate limit. If the pKa of the leaving group is > 15, phosphorylation is rate limiting. A Bronsted plot of log kcat vs pKa of the leaving group for those substrates for which phosphorylation is rate limiting yields a beta lg of approximately -0.6. In contrast to the wild-type enzyme, the log kcat values for the S102C mutant enzyme catalyzing the hydrolysis of phosphate esters are linearly dependent on the pKa's of the leaving group throughout the range of pKa from 4 to 16. Phosphorylation of C102 is the rate controlling step, and kcat is independent of the Tris concentration as predicted for rate limiting phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Dependence of the phosphorylation of alkaline phosphatase by phosphate monoesters on the pKa of the leaving group. 770 37

Reaction products of calf thymus DNA with (1R,2S,3S)-3-methylcyclohexanediamineplatinum (abbreviated as Pt(RSS-dach)Cl2) were investigated by enzymatic degradation of the platinated DNA and subsequent HPLC analysis. Five platinated adducts involving d(GpG), d(ApG) and (dG)2 residues were identified by HPLC after complete digestion using deoxyribonuclease I, nuclease P1, and alkaline phosphatase. The adducts with d(GpG) and d(ApG) consisted of two geometrical isomers, because Pt(RSS-dach)Cl2 lacks a C2 symmetry element. The d(GpG) and d(ApG) adducts were intrastrand compounds crosslinked between the N7 atoms of the adjacent purine bases. The two d(GpG) adducts were most abundant and comprised more than 65% of all the platinated adducts. The relative ratio of the two d(GpG) isomers was 3:2 for reaction with DNA, whereas the ratio was 1:1 for reaction with a single stranded oligonucleotide. The detailed structure of the two d(GpG) adducts is also described based on NMR spectroscopic data.
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PMID:Reaction of (1R,2S,3S)-3-methylcyclohexanediamineplatinum(II) with DNA: isolation and characterization of the platinum-nucleotide adducts by means of HPLC and NMR spectroscopy. 772 26

Polyphosphate metabolism in Escherichia coli was studied in order to determine the role of polyphosphates in energy and phosphate metabolism. Phosphate-shift experiments were performed on wild-type E. coli W3110 and on an E. coli strain mutant in the genes encoding the polyphosphate-metabolizing enzymes polyphosphate kinase (PPK) and polyphosphatase (PPX). The levels of polyphosphates were measured by [31P]NMR, and the activities of PPK and PPX were measured using enzymatic assays. During phosphate starvation, the intracellular level of polyphosphate was not detectable in E. coli W3110; the activities of PPX and alkaline phosphatase were high relative to those during exponential growth. During the shift from phosphate starvation to phosphate surplus conditions, PPX activity decreased and PPK activity and intracellular polyphosphate stores increased dramatically. These results imply an important role for polyphosphates in cellular energy and phosphate storage and in adaptation to adverse growth conditions.
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PMID:Polyphosphate metabolism in Escherichia coli. 783 34

Benzamide riboside exhibits significant cytotoxicity against a variety of human tumor cells in culture. On the basis of metabolic studies, the primary target of this drug's action appears to be IMP dehydrogenase (IMPDH). Incubation of human myelogenous leukemia K562 cells with an IC50 concentration of benzamide riboside resulted in an expansion of IMP pools (5.9-fold), with a parallel reduction in the concentration of GMP (90%), GDP (63%), GTP (55%) and dGTP (40%). On kinetic grounds, it was deduced that benzamide riboside (whose Ki versus IMPDH is 6.4 mM, while that of its 5'-monophosphate is 3.9 mM) or its 5'-monophosphate were unlikely to be responsible for inhibition of this target enzyme, IMPDH, since only micromolar concentrations of benzamide riboside were needed to exert potent inhibition of tumor-cell growth. Studies on the metabolism of this C-nucleoside have revealed the presence of a new peak eluting in the nucleoside diphosphate area on HPLC. Treatment of this peak with venom phosphodiesterase degraded it and concurrently nullified its inhibitory activity versus IMPDH; alkaline phosphatase, on the other hand, totally failed to digest the anabolite. These results suggest that the metabolite in question is the phosphodiester, benzamide adenine dinucleotide (BAD). Evidence that the inhibitor was an analog of NAD, wherein the nicotinamide moiety has been replaced by benzamide, was provided by both NMR and mass spectrometric analysis and confirmed by enzymatic synthesis. Further insight into the nature of the active principle was obtained from kinetic studies, which established that BAD competitively inhibited NAD utilization by partially purified IMPDH from K562 cells with a Ki of 0.118 microM. In concert, these studies establish that benzamide riboside exhibits potent antiproliferative activity by inhibiting IMPDH through BAD.
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PMID:Cytotoxicity and characterization of an active metabolite of benzamide riboside, a novel inhibitor of IMP dehydrogenase. 790 81

The protozoan parasite Leishmania mexicana secretes a heavily glycosylated 100-kDa acid phosphatase (sAP) which is associated with one or more polydisperse proteophosphoglycans. Most of the glycans in this complex were released using mild acid hydrolysis conditions that preferentially cleave phosphodiester linkages. The released saccharides were shown to consist of monomeric mannose and a series of neutral and phosphorylated glycans by Dionex high performance liquid chromatography, methylation analysis, exoglycosidase digestions, and one-dimensional 1H NMR spectroscopy. The neutral species comprised a linear series of oligosaccharides with the structures [Man alpha 1-2]1-5Man. The phosphorylated oligosaccharides were characterized as PO4-6Gal beta 1-4Man and PO4-6[Glc beta 1-3]Gal beta 1-4Man. The attachment of these glycans to the polypeptide backbone via the linkage, Man alpha 1-PO4-Ser, is suggested by: 1) the finding that more than 60% of the serine residues in the polypeptide are phosphorylated and 2) the resistance of the phosphoserine residues to alkaline phosphatase digestion unless the sAP was first treated with either mild acid (to release all glycans) or jack bean alpha-mannosidase (to release neutral mannose glycans). Analysis of the partially resolved components of the complex indicated that the most of the O-linked glycans on the 100-kDa phosphoglycoprotein comprised mannose and the mannose-oligosaccharides. In contrast the major O-linked glycans on the proteophosphoglycan were short phosphoglycan chains, containing on average two repeat units per chain. In addition to the O-linked glycans, both components in the sAP complex contained N-linked glycans. The N-glycanase F-released glycans were characterized by Bio-Gel P4 chromatography and exoglycosidase digestions to be the biantennary oligomannose type with the structures Glc1Man6GlcNAc2 and Man6GlcNAc2. The O-linked glycans of the sAP complex are similar to those found in the phosphoglycan chains of the abundant surface lipophosphoglycan, but differ in having much shorter phosphoglycan chains and a more diverse series of mannose cap oligosaccharides. These data suggest that there are marked differences in the ability of different glycosyltransferases to utilize peptide-linked versus glycolipid-linked acceptors.
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PMID:O- and N-glycosylation of the Leishmania mexicana-secreted acid phosphatase. Characterization of a new class of phosphoserine-linked glycans. 792 59


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