Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Diphosphates”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed2004

Identification of an Archaeal type II isopentenyl diphosphate isomerase in methanothermobacter thermautotrophicus.

Isopentenyl diphosphate (IPP):dimethylallyl diphosphate isomerase catalyzes the interconversion of the fundamental five-carbon homoallylic and allylic diphosphate building blocks required for biosynthesis of isoprenoid compounds. Two different isomerases have been reported. The type I enzyme, first characterized in the late 1950s, is widely distributed in eukaryota and eubacteria. The type II enzyme was recently discovered in Streptomyces sp. strain CL190. Open reading frame 48 (ORF48) in the archaeon Methanothermobacter thermautotrophicus encodes a putative type II IPP isomerase. A plasmid-encoded copy of the ORF complemented IPP isomerase activity in vivo in Salmonella enterica serovar Typhimurium strain RMC29, which contains chromosomal knockouts in the genes for type I IPP isomerase (idi) and 1-deoxy-D-xylulose 5-phosphate (dxs). The dxs gene was interrupted with a synthetic operon containing the Saccharomyces cerevisiae genes erg8, erg12, and erg19 allowing for the conversion of mevalonic acid to IPP by the mevalonate pathway. His6-tagged M. thermautotrophicus type II IPP isomerase was produced in Escherichia coli and purified by Ni2+ chromatography. The purified protein was characterized by matrix-assisted laser desorption ionization mass spectrometry. The enzyme has optimal activity at 70 degrees C and pH 6.5. NADPH, flavin mononucleotide, and Mg2+ are required cofactors. The steady-state kinetic constants for the archaeal type II IPP isomerase from M. thermautotrophicus are as follows: K(m), 64 microM; specific activity, 0.476 micromol mg(-1) min(-1); and k(cat), 1.6 s(-1).

Amino Acid Sequence↗
PubMed1966

Properties of a Mutant of Escherichia coli with a Temperature-sensitive Fructose-1,6-Diphosphate Aldolase.

Böck, August (Purdue University, Lafayette, Ind.), and Frederick C. Neidhardt. Properties of a mutant of Escherichia coli with a temperature-sensitive fructose-1,6-diphosphate aldolase. J. Bacteriol. 92:470-476. 1966.-A mutant of Escherichia coli in which fructose-1,6-diphosphate aldolase functions at 30 C but not at 40 C was used to study the physiological effect of a specific block in the Embden-Meyerhof glycolytic pathway. Growth of the mutant at 40 C was found to be inhibited by the presence of glucose or certain related compounds in the medium. At 40 C, glucose was metabolized at 30 to 40% of the control rate and was abnormal in that glucose was converted into other six-carbon substances (probably gluconate, in large part) that were released into the culture medium. The inhibition was complete, but transient; its duration depended upon the initial amount of inhibitor added. The resumption of growth at 40 C was correlated with the further catabolism of the excreted compounds. When glycerol was used to grow the mutant at 40 C, the growth inhibition by glucose was accompanied by cessation of glycerol metabolism. Growth on alpha-glycerol phosphate was not inhibited under these conditions, implicating glycerol kinase as a possible site of inhibition; no inhibition of glycerol kinase by sugar phosphates, however, could be detected in vitro. The inhibitory effect of glucose on growth at 40 C is not caused by a deficit of intracellular adenosine triphosphate, but may be the result of a generalized poisoning of many cell processes by a greatly increased intracellular concentration of fructose-1,6-diphosphate, the substrate of the damaged enzyme.

Journal Article↗
PubMed1976

Synthesis of guanosine 5'-triphosphate,3'-diphosphate in a spo T strain of Escherichia coli.

A spo T stringent strain of Escherichia coli rapidly accumulates guanosine 5'-triphosphate,3'-diphosphate (pppGpp) immediately after the onset of isoleucine starvation. Subsequently, its level rapidly falls, as guanosine 5'-diphosphate,3'-diphosphate (ppGpp) continues to rise to the maximum value, which is abnormally high compared with that in the spo T+ strain. The ppGpp level in the spo T strain never reaches a steady state as it does in the spo T+ strain. Immediately after starvation, pppGpp and ppGpp are labeled with [3H]guanosine at a similar differential rate in both the spo T and spo T+ strains, suggesting that the two strains synthesize these nucleotides by the same pathway. However, by 15 min after starvation, the synthesis of these nucleotides is nearly halted in the spo T strain, and is greatly reduced in the spo T+ strain. Since ppGpp is labeled with [3H]guanosine more slowly than pppGpp in the starved spo T+ strain, ppGpp cannot be a precursor of pppGpp. The kinetics of the GTP level during starvation suggests that GTP is a precursor of pppGpp. The observed differences between the spo T and spo T+ strains can be explained by postulating, firstly, that ppGpp negatively controls the conversion of GTP to pppGpp, which is subsequently converted to ppGpp; secondly, that a catabolite of ppGpp negatively controls the conversion of pppGpp to ppGpp; and thirdly, that the spo T mutation primarily reduces the rate of ppGpp catabolism.

Escherichia coli↗
PubMed1975

Effect of desdanine on nucleoside diphosphate kinase and pyruvate kinase of Escherichia coli.

Kinetic analysis demonstrated that the irreversible inhibition of nucleoside diphosphate kinase of Escherichia coli by desdanine proceeds via a reversible Enzyme-Inhibitor complex. It is known that pyruvate kinase of E. coli becomes inactive upon prolonged dialysis in the absence of a reducing reagent, such as dithiothreitol and that the inactive enzyme is reactivated if dithiothretiol is added. Desdanine inhibits this reactivation process. The effect is discussed in relation to inhibition in relation to the inhibition of growth of E. coli by desdanine under anaerobic conditions. Pyruvate kinase of E. coli changes not only in intracellular quantity but in its kinetic characteristics depending on growth conditions, aerobic or anaerobic. The enzyme shows a broad specificity for nucleside diphosphates, especially in the presence of AMP, and thus resembles closely nucleoside diphosphate kinase. The in vivo role of pyruvate kinase in supplying nucleoside triphosphates under anaerobic conditions is discussed.

Acrylamides↗
PubMed2004

Presence of copalyl diphosphate synthase gene in an actinomycete possessing the mevalonate pathway.

We have previously shown that gene clusters for biosyntheses of terpentecin and BE-40644, a diterpene antibiotic and a sesquiterpene antibiotic, respectively, were located in the adjacent mevalonate pathway gene clusters. In this study, a mevalonate pathway gene cluster was cloned from Streptomyces sp. strain KO-3988, which was known to produce furaquinocin A, employing a hybridization experiment using a 3-hydroxy-3-methyl glutaryl CoA (HMG-CoA) reductase gene, which had been previously cloned from the strain KO-3988, as a probe. By sequencing flanking regions, we found four open reading frames that could encode a putative cytochrome P450 (ORF1), an isoprenoid cyclase (ORF2), an unknown protein (ORF3), and a polyprenyl diphosphate synthase gene (ORF4) in the upstream region of the mevalonate pathway gene cluster, though we did not find any genes related to furaquinocin A biosynthesis. The two ORFs (ORF2 and 4) were expressed as recombinant enzymes in E. coli and used for studies to investigate functions of these products. The ORF4 product was confirmed to be a geranylgeranyl diphosphate (GGDP, C20) synthase. The ORF2 product proved to catalyze a conversion of GGDP into copalyl diphosphate, the first example of an enzyme with this function of prokaryotic origin. These results again showed that actinomycetes possessing the mevalonate pathway usually produce an isoprenoid and that its biosynthetic gene cluster exists in adjacent the mevalonate pathway gene cluster.

Alkyl and Aryl Transferases↗
PubMed1998

[Clinical study of fructose 1,6-diphosphate on myocardial ischemia/reperfusion injuries].

Twenty ventricular septal defect patients who underwent cardiopulmonary bypass (CPB) were divided into 1,6-diphosphate group and controlled group (10 cases each). Blood samples were taken at pre- and post-cardiopulmonary bypass 30 min, 6 h, and 24 h to determine lactate dehydrogenase enzyme(LDH), creatine kinase enzyme(CK) and its isoenzyme(CK-MB) levels. We found that 1,6-diphosphate decreased the increasing levels of LDH, CK, and CK-MB after cardiopulmonary bypass. It is suggested that 1,6-diphosphate may attenuate myocardial ischemia/reperfusion injuries during cardiopulmonary bypass.

Cardioplegic Solutions↗
PubMed1977

[The effect of chloroquine diphosphate upon tissue mast cells in rat's skin (author's transl)].

The number and morphological changes of the mast cells were studied in the skin of three groups white rats. The first group was treated subcutaneously with 5 mg/kg body weight chloroquine diphosphate for twenty days, the second group was treated with saline; the third group was not treated at all. An absolute increase of the number of mast cells in the animals treated with chloroquine diphosphate was established. It was assumed the increase of the mast cells is connected with the activation of the histidine-decarboxylase and the rise of the histamine level in the site of chloroquine diphosphate application.

Animals↗
PubMed2004

Cloning and functional analysis of a cDNA encoding Ginkgo biloba farnesyl diphosphate synthase.

Farnesyl diphosphate synthase (FPS; EC2.5.1.1/EC2. 5.1.10) catalyzes the synthesis of farnesyl diphosphate, and provides precursor for biosynthesis of sesquiterpene and isoprenoids containing more than 15 isoprene units in Ginkgo biloba. Here we report the cloning, characterization and functional analysis of a new cDNA encoding FPS from G. biloba. The full-length cDNA (designated GbFPS) had 1731 bp with an open reading frame of 1170 bp encoding a polypeptide of 390 amino acids. The deduced GbFPS was similar to other known FPSs and contained all the conserved regions of trans-prenyl chain-elongating enzymes. Structural modeling showed that GbFPS had the typical structure of FPS, the most prominent feature of which is the arrangement of 13 core helices around a large central cavity. Southern blot analysis revealed a small FPS gene family in G. biloba. Expression analysis indicated that GbFPS expression was high in roots and leaves, and low in stems. Functional complementation of GbFPS in an FPS-deficient strain confirmed that GbFPS mediates farnesyl diphosphate biosynthesis.

Alkyl and Aryl Transferases↗
PubMedDate not supplied

[An intron-free methyl jasmonate inducible geranylgeranyl diphosphate synthase gene from Taxus media and its functional identification in yeast].

Geranylgeranyl diphosphate synthase (GGPPS, EC: 2.5.1.29) catalyzes the biosynthesis of geranylgeranyl diphosphate (GGPP), which is a key precursor for diterpenes including Taxol, one of the most potent antitumor drugs. In order to investigate the role of GGPP synthase in taxol biosynthesis, we cloned, characterized and functionally expressed the GGPP synthase gene from Taxus media. A 3743-bp genomic sequence of T. media was isolated by genome walking strategy which contained an 1182-bp open reading frame (ORF) encoding a 393-amino acid polypeptide that showed high similarity to other plant GGPPSs. Subsequently the full-length cDNA of the GGPPS gene of T. media (designated TmGGPPS) was amplified by RACE. Bioinformatic analysis showed that TmGGPPS was an intron-free gene and its deduced polypeptide contained all the five conserved domains and functional aspartate-rich motifs of the prenyltransferases. By constructing the phylogenetic tree of plant GGPPSs, it was found that plant-derived GGPPSs could be divided into two classes, angiosperm and gymnosperm classes, which might have evolved in parallel from the same ancestor. To our knowledge this was the first report that the geranylgeranyl diphosphate synthase genes were free of intron and evolved in parallel between angiosperms and gymnosperms. The coding sequence of TmGGPPS was expressed in yeast mutant (SFNY368) lacking of GGPP synthase activity through functional complementation, and the transgenic yeast showed to have activity of GGPP synthase. This was also the first time to use SFNY368 to identify the function of plant-derived GGPPSs. Furthermore, investigation of the impact of methyl jasmonate (MeJA) on the expression of TmGGPPS revealed that MeJA-treated T. media cultured cells had much higher expression of TmGGPPS than untreated cells.

Acetates↗
PubMed2005

Cloning and expression of a farnesyl diphosphate synthase in Centella asiatica (L.) Urban.

A cDNA encoding farnesyl diphosphate synthase (FPS; EC2.5.1.1/EC2.5.1.10) was isolated from Centella asiacita (L.) Urban, using degenerate primers based on two highly conserved domains. A full-length cDNA clone was subsequently isolated by rapid amplification of cDNA ends (RACE) PCR. The sequence of the CaFPS (C. asiatica farnesyl diphosphate synthase) cDNA contains an open reading frame of 1029 nucleotides encoding 343 amino acids with a molecular mass of 39.6 kDa. The deduced CaFPS amino acid sequence exhibits 84, 79, and 72%, identity to the FPSs of Artemisia annua, Arabidopsis thaliana, and Oryza sativa, respectively. Southern blot analysis suggested that the C. asiatica genome contains only one FPS gene. An artificially expressed soluble form of the CaFPS was identified by SDS-PAGE. It had high specific activity and produced farnesyl diphosphate as the major isoprenoid.

Alkyl and Aryl Transferases↗
PubMedDate not supplied

[Metabolism and toxicity of various xenobiotics in vitamin B1 deficiency and after administration of thiamine and thiamine diphosphate].

Metabolism of aminopyrine, sodium benzoate and toxicity of cyclophosphamide were studied in 185 male rats under conditions of various content of vitamin B1 in the animals. Deficiency of thiamin led to an increase in excretion of 4-aminoantipyrine and especially of its acetylated derivative. After administration of thiamin metabolism of aminopyrine was not distinctly altered, while thiamin diphosphate inhibited the drug biotransformation. In deficiency of vitamin B1 transformation of benzoic acid into hippuric acid was inhibited but formation of glucuronides was elevated. Administration of thiamin or thiamin diphosphate stimulated the benzoic acid conjugation and inhibited the glucuronides formation. Deficiency of vitamin B1 accelerated the cyclophosphamide toxicity. Preadministration of thiamin and especially of thiamin diphosphate decreased the toxic effect of cyclophosphamide.

Aminopyrine↗
PubMed1979

A new nucleotide involved in the stringent response in Escherichia coli. Guanosine 5'-diphosphate-3'-monophosphate.

A novel nucleotide has been detected in Escherichia coli subjected to the stringent response. However, this nucleotide does not accumulate in relA+ cells subjected to heat shock, in which guanosine 5'-diphosphate-3'-diphosphate does accumulate but stable RNA synthesis is not restricted. The intracellular level of this new nucleotide thus correlates well with control of stable RNA synthesis. Chemical and enzymatic analysis shows that the new nucleotide is guanosine 5'-diphosphate-3'-monophosphate. It is suggested that this nucleotide may play a role in stringent control of stable RNA synthesis.

Escherichia coli↗
PubMed1985

Nucleoside 5'-diphosphates as effectors of mammalian ribonucleotide reductase.

It was found that nucleoside 5'-diphosphates could serve as effectors of ribonucleotide reductase. ADP was an activator of CDP reduction; ADP reduction was activated by dGDP; GDP reduction was activated by dTDP. Conversely, dADP inhibited the reduction of CDP, UDP, GDP, and ADP; dGDP inhibited UDP and GDP reductions; and dTDP inhibited UDP reduction. The inhibition of UDP reduction by dADP, dTDP, and dGDP was at least equal to that observed for dATP, dTTP, and dGTP, respectively. In these experiments with the nucleoside diphosphates as effectors, high-pressure liquid chromatography analysis of the reaction mixtures showed that no nucleoside 5'-triphosphates were found during the reaction period which could account for the effects seen with the nucleoside diphosphates as effectors. Further experiments were carried out in which adenyl-5'-yl imidodiphosphate was used as the positive effector of CDP and UDP reductions in place of ATP. Under these conditions, CDP and UDP reductions were inhibited by dADP, dTDP, and dGDP to the same extent observed in the presence of ATP. ADP served not only as a substrate for ribonucleotide reductase but also as an activator of CDP and UDP reductions. The direct products (dNDPs) also served as positive and negative effectors. Dixon plots indicated that the dNDPs were acting as noncompetitive inhibitors with respect to the substrate. ADP increased the sedimentation velocity of the ribonucleotide reductase in a manner similar to ATP. These data are consistent with the allosteric effects seen with the nucleoside 5'-triphosphates. Additionally, from the thorough study of the role of effectors on UDP reduction, it is clear that UDP reduction was most sensitive to the negative effectors dATP, dADP, dTTP, dTDP, dGTP, and dGDP.

Animals↗
PubMed1983

Guanosine 5'-triphosphate, 3'-diphosphate 5'-phosphohydrolase. Purification and substrate specificity.

The regulatory nucleotide guanosine 5'-diphosphate, 3'-diphosphate (ppGpp) and its precursor guanosine 5'-triphosphate, 3'-diphosphate (pppGpp) are accumulated during stringent response in bacterial cells. The enzyme pppGpp-5'-phosphohydrolase, which catalyzes the conversion of pppGpp to ppGpp, was partially purified from Escherichia coli. It has Mr = 140,000 and an apparent Km of 0.11 mM for pppGpp. It requires Mg2+ and a monovalent cation. NH4+ is preferred over K+, while Na+ is inactive. The enzyme does not hydrolyze GTP, ATP, pppApp, or ppGpp. It is also not effectively inhibited by these nucleotides. pppGpp-5'-phosphohydrolase hydrolyzes the 3'-monophosphate analog pppGp equally well (apparent Km of 0.13 mM), yielding the recently identified MS III nucleotide (ppGp). pppGpp-5'-phosphohydrolase does not have RNA 5'-terminal gamma-phosphatase activity; however, 5'-terminal phosphates are released by pppGpp-5'-phosphohydrolase when the GTP-terminated RNA chains are first converted into oligonucleotides by RNase A treatment. pppGpp-5'-phosphohydrolase was found to actively hydrolyze the dinucleotide fragment pppGpNp but exhibited very low activity toward longer chain fragments. The 3'-unphosphorylated dinucleotide pppGpN was, however, not hydrolyzed. The ability of pppGpp-5'-phosphohydrolase to hydrolyze pppGpp, pppGp, and pppGpNp, but not pppG and pppGpN, indicates that pppGpp-5'-phosphohydrolase is rather nonspecific toward the 3'-OH substitutions of the substrates although a free, unsubstituted phosphate group at the 3'-OH position is essential.

Cations, Monovalent↗
PubMed1984

Influence of sex and sex steroids on bilirubin uridine diphosphate-glucuronosyltransferase activity of rat liver.

Bilirubin uridine diphosphate-glucuronosyltransferase activity was markedly higher in liver preparations of adult female rats when compared with adult male rats. Ovariectomy decreased the levels in females whereas orchiectomy produced an increase in males. Totally opposite results were obtained when assaying p-nitrophenol uridine diphosphate-glucuronosyl-transferase; this suggests the existence of different enzymes. Administration of physiologic amounts of testosterone decreased enzyme activities in orchiectomized males to normal levels. Estradiol had no effect but progesterone significantly enhanced the transferase activity of gonadectomized females. The effect was more pronounced when progesterone was associated with estradiol. The combined treatment of ovariectomized rats resulted in physiologic plasma levels of sex steroids and could increase the levels of glucuronosyl-transferase to values of normal females. Male and female sex hormones thus exert opposite effects on bilirubin uridine diphosphate-glucuronosyltransferase. If applicable to humans, this might explain the differences in serum bilirubin levels in adult men and women, and in the prevalence of Gilbert's syndrome.

Animals↗
PubMed1984

Anaerobic expression of maize fructose-1,6-diphosphate aldolase.

The anaerobic proteins of maize are a set of 10 major and 10 minor polypeptides selectively synthesized in anaerobic seedling roots. 1) Anaerobiosis resulted in the selected labeling of a protein which bound to Blue Sepharose and was eluted by fructose 1,6-diphosphate. 2) This protein elicited antiserum which recognized a single protein with molecular weight of approximately 40,000. 3) By Western blot analysis, this antiserum recognized a maize fructose-1,6-diphosphate aldolase purified to homogeneity. We show that two major anaerobic proteins of maize, ANP35.5 and ANP33A, correspond to a cytoplasmic fructose-1,6-diphosphate aldolase.

Anaerobiosis↗
PubMed1982

Pharmacokinetics of fructose-1, 6-diphosphate in the rat.

The pharmacokinetics of fructose-1, 6-diphosphate administered to the rat by intravenous injection was studied. Labelled fructose-1, 6-diphosphate was measured in blood, where it reaches the highest amount 10 min after administration, and in different organs. Residual radioactivity was measured in organs 20 min after administration, the highest values being found in the kidney and the lowest in the brain. The hydrolytic activity of the various organs toward fructose-1, 6-diphosphate was measured in organ extracts and was found to be maximal in the kidney and minimal in the brain.

Animals↗
PubMedDate not supplied

[Separation of the enzyme catalyzing polymerization of deoxyribonucleoside diphosphates from preparations of E. coli DNA-polymerase I].

The enzyme which catalyses template independent synthesis of polydeoxynucleotides from deoxynucleoside diphosphates was separated from E. coli DNA polymerase I by DEAE-cellulose chromatography followed by ultrafiltration through the M-50 Amicon filter. The ultrafiltration data indicate that the molecular weight of the enzyme is not higher than 50,000. The enzyme is not able to use deoxynucleoside triphosphates, ribonucleoside di- or triphosphates as substrates for the polymerization. The reaction of template independent polymerization proceeds with a lag period varying from 2 to 20 hours (for different preparations of enzyme) and is activated by Mg2+ (the optimal concentration 1-2 . 10(-3) M). The pH optimum of the reaction is at 8.5. The optimal concentration of deoxyribonucleoside diphosphates is 10(-3) M, and its increase strongly inhibits polymerization. The enzyme was supposed to be called deoxynucleoside diphosphate: olygonucleotide deoxynucleotidyltransferase (catalyzing polymerization without template). The presence of the enzyme in the preparations of E. coli DNA-polymerase I can explain the ability of the latter to catalyze the untemplated synthesis of poly dG : poly dC.

DNA Polymerase I↗