A Nutrient Combination That Can Affect Synapse Formation
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Nucleotide Degradation
Nucleotide Degradation Nucleotide Degradation The Digestion Pathway • Ingestion of food always includes nucleic acids. • As you know from BI 421, the low pH of the stomach does not affect the polymer. • In the duodenum, zymogens are converted to nucleases and the nucleotides are converted to nucleosides by non-specific phosphatases or nucleotidases. nucleases • Only the non-ionic nucleosides are taken & phospho- diesterases up in the villi of the small intestine. Duodenum Non-specific phosphatases • In the cell, the first step is the release of nucleosides) the ribose sugar, most effectively done by a non-specific nucleoside phosphorylase to give ribose 1-phosphate (Rib1P) and the free bases. • Most ingested nucleic acids are degraded to Rib1P, purines, and pyrimidines. 1 Nucleotide Degradation: Overview Fate of Nucleic Acids: Once broken down to the nitrogenous bases they are either: Nucleotides 1. Salvaged for recycling into new nucleic acids (most cells; from internal, Pi not ingested, nucleic Nucleosides acids). Purine Nucleoside Pi aD-Rib 1-P (or Rib) 2. Oxidized (primarily in the Phosphorylase & intestine and liver) by first aD-dRib 1-P (or dRib) converting to nucleosides, Bases then to –Uric Acid (purines) –Acetyl-CoA & Purine & Pyrimidine Oxidation succinyl-CoA Salvage Pathway (pyrimidines) The Salvage Pathways are in competition with the de novo biosynthetic pathways, and are both ANABOLISM Nucleotide Degradation Catabolism of Purines Nucleotides: Nucleosides: Bases: 1. Dephosphorylation (via 5’-nucleotidase) 2. Deamination and hydrolysis of ribose lead to production of xanthine. 3. Hypoxanthine and xanthine are then oxidized into uric acid by xanthine oxidase. Spiders and other arachnids lack xanthine oxidase. -
Monophosphate- Binding Protein Complex with Subsequent Poly(A) RNA Synthesis in Embryonic Chick Cartilage
Specific nuclear binding of adenosine 3',5'-monophosphate- binding protein complex with subsequent poly(A) RNA synthesis in embryonic chick cartilage. W M Burch Jr, H E Lebovitz J Clin Invest. 1980;66(3):532-542. https://doi.org/10.1172/JCI109885. Research Article We used embryonic chick pelvic cartilage as a model to study the mechanism by which cyclic AMP increases RNA synthesis. Isolated nuclei were incubated with [32P]-8-azidoadenosine 3,5'-monophosphate ([32P]N3cAMP) with no resultant specific nuclear binding. However, in the presence of cytosol proteins, nuclear binding of [32P]N3cAMP was demonstrable that was specific, time dependent, and dependent on a heat-labile cytosol factor. The possible biological significance of the nuclear binding of the cyclic AMP-protein complex was identified by incubating isolating nuclei with either cyclic AMP or cytosol cyclic AMP-binding proteins prepared by batch elution DEAE cellulose chromatography (DEAE peak cytosol protein), or both, in the presence of cold nucleotides and [3H]uridine 5'-triphosphate. Poly(A) RNA production occurred only in nuclei incubated with cyclic AMP and the DEAE peak cytosol protein preparation. Actinomycin D inhibited the incorporation of [3H]uridine 5'-monophosphate into poly(A) RNA. The newly synthesized poly(A) RNA had a sedimentation constant of 23S. Characterization of the cytosol cyclic AMP binding proteins using [32P]N3-cAMP with photoaffinity labeling three major cAMP-binding complexes (41,000, 51,000, and 55,000 daltons). The 51,000 and 55,000 dalton cyclic AMP binding proteins were further purified by DNA-cellulose chromatography. In the presence of cyclic AMP they stimulated poly(A) RNA synthesis in isolated nuclei. -
Allopurinol Sodium) for Injection 500 Mg
ALOPRIM® (allopurinol sodium) for Injection 500 mg [al'-ō-prĭm] For Intravenous Infusion Only Rx only DESCRIPTION: ALOPRIM (allopurinol sodium) for Injection is the brand name for allopurinol, a xanthine oxidase inhibitor. ALOPRIM (allopurinol sodium) for Injection is a sterile solution for intravenous infusion only. It is available in vials as the sterile lyophilized sodium salt of allopurinol equivalent to 500 mg of allopurinol. ALOPRIM (allopurinol sodium) for Injection contains no preservatives. The chemical name for allopurinol sodium is 1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin 4-one monosodium salt. It is a white amorphous mass with a molecular weight of 158.09 and molecular formula C5H3N4NaO. The structural formula is: The pKa of allopurinol sodium is 9.31. CLINICAL PHARMACOLOGY: Allopurinol acts on purine catabolism without disrupting the biosynthesis of purines. It reduces the production of uric acid by inhibiting the biochemical reactions immediately preceding its formation. The degree of this decrease is dose dependent. Allopurinol is a structural analogue of the natural purine base, hypoxanthine. It is an inhibitor of xanthine oxidase, the enzyme responsible for the conversion of hypoxanthine to xanthine and of xanthine to uric acid, the end product of purine metabolism in man. Allopurinol is metabolized to the corresponding xanthine analogue, oxypurinol (alloxanthine), which also is an inhibitor of xanthine oxidase. Reutilization of both hypoxanthine and xanthine for nucleotide and nucleic acid synthesis is markedly enhanced when their oxidations are inhibited by allopurinol and oxypurinol. This reutilization does not disrupt normal nucleic acid anabolism, however, because feedback inhibition is an integral part of purine biosynthesis. -
Mechanisms of Synthesis of Purine Nucleotides in Heart Muscle Extracts
Mechanisms of Synthesis of Purine Nucleotides in Heart Muscle Extracts David A. Goldthwait J Clin Invest. 1957;36(11):1572-1578. https://doi.org/10.1172/JCI103555. Research Article Find the latest version: https://jci.me/103555/pdf MECHANISMS OF SYNTHESIS OF PURINE NUCLEOTIDES IN HEART MUSCLE EXTRACTS1 BY DAVID A. GOLDTHWAIT2 (From the Departments of Biochemistry and Medicine, Western Reserve University, Cleveland, Ohio) (Submitted for publication February 18, 1957; accepted July 18, 1957) The key role of ATP, a purine nucleotide, in 4. Adenine or Hypoxanthine + PRPP -> AMP the conversion of chemical energy into mechanical or Inosinic Acid (IMP) + P-P. work by myocardial tissue is well established (1, The third mechanism of synthesis is through the 2). The requirement for purine nucleotides has phosphorylation of a purine nucleoside (8, 9): also been demonstrated in the multiple synthetic 5. Adenosine + ATP -, AMP + ADP. reactions which maintain all animal cells in the Several enzymatic mechanisms are known which steady state. Since the question immediately arises result in the degradation of purine nucleotides and whether the purine nucleotides are themselves in nucleosides. The deamination of adenylic acid is a steady state, in which their rates of synthesis well known (10): equal their rates of degradation, it seems reason- 6. AMP -* IMP + NH8. able to investigate first what mechanisms of syn- Non-specific phosphatases (11) as well as spe- thesis and degradation may be operative. cific 5'-nucleotidases (12) have been described At present, there are three known pathways for which result in dephosphorylation: the synthesis of purine nucleotides. The first is 7. -
A Previously Undescribed Pathway for Pyrimidine Catabolism
A previously undescribed pathway for pyrimidine catabolism Kevin D. Loh*†, Prasad Gyaneshwar*‡, Eirene Markenscoff Papadimitriou*§, Rebecca Fong*, Kwang-Seo Kim*, Rebecca Parales¶, Zhongrui Zhouʈ, William Inwood*, and Sydney Kustu*,** *Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, CA 94720-3102; ¶Section of Microbiology, 1 Shields Avenue, University of California, Davis, CA 95616; and ʈCollege of Chemistry, 8 Lewis Hall, University of California, Berkeley, CA 94720-1460 Contributed by Sydney Kustu, January 19, 2006 The b1012 operon of Escherichia coli K-12, which is composed of tive N sources. Here we present evidence that the b1012 operon seven unidentified ORFs, is one of the most highly expressed codes for proteins that constitute a previously undescribed operons under control of nitrogen regulatory protein C. Examina- pathway for pyrimidine degradation and thereby confirm the tion of strains with lesions in this operon on Biolog Phenotype view of Simaga and Kos (8, 9) that E. coli K-12 does not use either MicroArray (PM3) plates and subsequent growth tests indicated of the known pathways. that they failed to use uridine or uracil as the sole nitrogen source and that the parental strain could use them at room temperature Results but not at 37°C. A strain carrying an ntrB(Con) mutation, which Behavior on Biolog Phenotype MicroArray Plates. We tested our elevates transcription of genes under nitrogen regulatory protein parental strain NCM3722 and strains with mini Tn5 insertions in C control, could also grow on thymidine as the sole nitrogen several genes of the b1012 operon on Biolog (Hayward, CA) source, whereas strains with lesions in the b1012 operon could not. -
Effects of Allopurinol and Oxipurinol on Purine Synthesis in Cultured Human Cells
Effects of allopurinol and oxipurinol on purine synthesis in cultured human cells William N. Kelley, James B. Wyngaarden J Clin Invest. 1970;49(3):602-609. https://doi.org/10.1172/JCI106271. Research Article In the present study we have examined the effects of allopurinol and oxipurinol on thed e novo synthesis of purines in cultured human fibroblasts. Allopurinol inhibits de novo purine synthesis in the absence of xanthine oxidase. Inhibition at lower concentrations of the drug requires the presence of hypoxanthine-guanine phosphoribosyltransferase as it does in vivo. Although this suggests that the inhibitory effect of allopurinol at least at the lower concentrations tested is a consequence of its conversion to the ribonucleotide form in human cells, the nucleotide derivative could not be demonstrated. Several possible indirect consequences of such a conversion were also sought. There was no evidence that allopurinol was further utilized in the synthesis of nucleic acids in these cultured human cells and no effect of either allopurinol or oxipurinol on the long-term survival of human cells in vitro could be demonstrated. At higher concentrations, both allopurinol and oxipurinol inhibit the early steps ofd e novo purine synthesis in the absence of either xanthine oxidase or hypoxanthine-guanine phosphoribosyltransferase. This indicates that at higher drug concentrations, inhibition is occurring by some mechanism other than those previously postulated. Find the latest version: https://jci.me/106271/pdf Effects of Allopurinol and Oxipurinol on Purine Synthesis in Cultured Human Cells WILLIAM N. KELLEY and JAMES B. WYNGAARDEN From the Division of Metabolic and Genetic Diseases, Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, North Carolina 27706 A B S TR A C T In the present study we have examined the de novo synthesis of purines in many patients. -
Metabolomics Identifies Pyrimidine Starvation As the Mechanism of 5-Aminoimidazole-4-Carboxamide-1- Β-Riboside-Induced Apoptosis in Multiple Myeloma Cells
Published OnlineFirst April 12, 2013; DOI: 10.1158/1535-7163.MCT-12-1042 Molecular Cancer Cancer Therapeutics Insights Therapeutics Metabolomics Identifies Pyrimidine Starvation as the Mechanism of 5-Aminoimidazole-4-Carboxamide-1- b-Riboside-Induced Apoptosis in Multiple Myeloma Cells Carolyne Bardeleben1, Sanjai Sharma1, Joseph R. Reeve3, Sara Bassilian3, Patrick Frost1, Bao Hoang1, Yijiang Shi1, and Alan Lichtenstein1,2 Abstract To investigate the mechanism by which 5-aminoimidazole-4-carboxamide-1-b-riboside (AICAr) induces apoptosis in multiple myeloma cells, we conducted an unbiased metabolomics screen. AICAr had selective effects on nucleotide metabolism, resulting in an increase in purine metabolites and a decrease in pyrimidine metabolites. The most striking abnormality was a 26-fold increase in orotate associated with a decrease in uridine monophosphate (UMP) levels, indicating an inhibition of UMP synthetase (UMPS), the last enzyme in the de novo pyrimidine biosynthetic pathway, which produces UMP from orotate and 5-phosphoribosyl- a-pyrophosphate (PRPP). As all pyrimidine nucleotides can be synthesized from UMP, this suggested that the decrease in UMP would lead to pyrimidine starvation as a possible cause of AICAr-induced apoptosis. Exogenous pyrimidines uridine, cytidine, and thymidine, but not purines adenosine or guanosine, rescued multiple myeloma cells from AICAr-induced apoptosis, supporting this notion. In contrast, exogenous uridine had no protective effect on apoptosis resulting from bortezomib, melphalan, or metformin. Rescue resulting from thymidine add-back indicated apoptosis was induced by limiting DNA synthesis rather than RNA synthesis. DNA replicative stress was identified by associated H2A.X phosphorylation in AICAr-treated cells, which was also prevented by uridine add-back. -
Effect of Uridine on Response of 5-Azacytidine-Resistant Human Leukemic Cells to Inhibitors of De Novo Pyrimidine Synthesis1
[CANCER RESEARCH 44, 5505-5510, December 1984] Effect of Uridine on Response of 5-Azacytidine-resistant Human Leukemic Cells to Inhibitors of de Novo Pyrimidine Synthesis1 S. Grant,2 K. Bhalla,3 and M. Gleyzer Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032 ABSTRACT activity is the most commonly encountered mode of resistance in animal systems (28). A uridine-cytidine kinase-deficient human promyelocytic leu- We have recently isolated a uridine-cytidine kinase-deficient, kemic subline (HL-60-5-aza-Cyd) has been isolated which is highly 5-aza-Cyd-resistant human promyelocytic leukemic sub- highly resistant to the antileukemic agent 5-azacytidine. Resist line (HL-60-5-aza-Cyd) (8) which is capable of surviving 5-aza- ant cells exposed to 10~5 M 5-azacytidine for 2 hr exhibit a Cyd concentrations (10~4 M) that exceed peak plasma levels in marked reduction in both the total ¡ntracellularaccumulation of humans (27). The purpose of the present studies was to assess 5-azacytidine (11.9 versus 156.0 pmol/106 cells) as well as its the metabolism of 5-aza-Cyd in these resistant cells and to incorporation into RNA (3.1 versus 43.4 pmol//ig o-ribose) com examine their response to a variety of clinically available inhibitors pared to the parent line. These biochemical changes are asso of de novo pyrimidine synthesis. Of the latter agents, PALA, an ciated with nearly a 100-fold decrease in sensitivity to the growth inhibitor of aspártele transcarbamylase (26), and pyrazofurin, an inhibitory effects of 5-azacytidine (concentration of drug associ ated with a 50% reduction in cell growth, 3.5 x 10~5 versus 5.0 inhibitor of orotidylate decarboxylase (5), are of particular inter x 10"7 M). -
Nucleotide Metabolism II
Nucleotide Metabolism II • Biosynthesis of deoxynucleotides • Salvage Pathway • Catabolism: Purines • Catabolism: Pyrimidines • Feedback inhibition in purine nucleotide biosynthesis CPS II • Cytosolic CPS II uses glutamine as the nitrogen donor to carbamoyl phosphate Regulation of pyrimidine synthesis •CPSII is allosterically regulated: PRPP and IMP are activators Several pyrimidines are inhibitors • Aspartate transcarbamoylase (ATCase) Important regulatory point in prokaryotes Catalyzes the first committed pathway step Allosteric regulators: CTP (-), CTP + UTP (-), ATP (+) • Regulation of pyrimidine nucleotide synthesis in E. coli Biosynthesis of deoxynucleotides • Uses diphosphates (ribo) • Ribonucleotide reducatase • 2 sub-units • R1- reduces, active and two allosteric sites (activity and specificity site) • R2- tyrosine radical carries electrons • removes 2' OH to H Ribonucleotide reductase reaction • removes 2' OH to H • Thioredoxin and NADPH used to regenerate sulfhydryl groups Thymidylate synthesis • UDP ------> dUMP • dUMP --------> dTMP • required THF • methylates uracil Regulation THF • Mammals cannot conjugate rings or synthesize PABA. • So must get in diet. • Sulfonamides effective in bacteria due to competitive inhibition of the incorporation of PABA Cancer Drugs • fluorouracil-- suicide inhibitor of Thy synthase • aminopterin • Methotrexate -- inhibits DHF reductase Salvage of Purines and Pyrimidines • During cellular metabolism or digestion, nucleic acids are degraded to heterocyclic bases • These bases can be salvaged -
Non-Utilization of Radioactive Lodinated Uracil, Uridine, and Orotic Acid by Animal Tissues in Vivo W
Non-utilization of Radioactive lodinated Uracil, Uridine, and Orotic Acid by Animal Tissues in Vivo W. H. PRUSOFF,WL. HOLMES,tANDA. D. WELCH Department of Pharmacology, School of Medicine, Western Reserve University, Cleveland, Ohio) Adenine (1, 6), guanine (1, 3, 5), cytidine (13), lometric localization of brain tumors. Further desoxycytidine (18), thymidine (18), and orotic more, an I'3-labeled oxazine dye had a significant acid (2), can be utilized by certain mammalian or effect in prolonging the life of mice bearing trans ganisms for the synthesis of nucleic acids ; and the planted tumors (19). If an effective and easily syn rate of incorporation of many of these compounds thesized radioactive iodine-labeled compound into the nucleic acids of rapidly growing tissues, could be found, the possibility might be afforded of such as regenerating liver or neoplastic tissues, is the comparable use of compounds labeled with greater than into those of resting tissues (10, 21). eka-iodine (astatine2@), a potent emitter of alpha Although 8-azaguanine is not a naturally occur particles, although this element is prepared with ring compound, evidence that it can be incorpo difficulty and has the inconveniently short half rated to a small extent into mammalian nucleic life of 7.5 hours (12). acids has been presented (16). This analog of gua Three P3-labeled pyrimidines, iodouridine-5- nine markedly inhibited the growth of Tetrahy I'S', iodouracil-5-I'31, and iodoorotic acid-5-P31, mena geleii, a guanine-requiring protozoan, and of were synthesized, and their incorporation into nor certain experimental tumors. Kidder et al. -
Effects of Salt Stress on Adenine and Uridine Nucleotide Pools, Sugar and Acid-Soluble Phosphate in Shoots of Pepper and Safflower
Journal of Experimental Botany, Vol. 39, No. 200, pp. 301-309, March 1988 Effects of Salt Stress on Adenine and Uridine Nucleotide Pools, Sugar and Acid-Soluble Phosphate in Shoots of Pepper and Safflower R. H. NIEMAN, R. A. CLARK, D. PAP, G. OGATA AND E. V. MAAS USDA, ARS, U.S. Salinity Laboratory, Riverside, California, U.S.A. Received 7 September 1987 ABSTRACT Nieman, R. H., Clark, R. A., Pap, D., Ogata, G. and Maas, E. V. 1988. Effects of salt stress on adenine and uridine nucleotide pools, sugar and acid-soluble phosphate in shoots of pepper and safflower.—J. exp. Bot. 39: 301-309. Pepper (Capsicum annuum cv. Yolo wonder) and safflower (Carthamus tmctonus L. cv. Gila) were 3 3 grown hydroponically and subjected to a salt stress (51 mol m" NaCl plus 25-5 mol m" CaCl2). Mature photosynthetic source leaves and shoot meristematic sinks (young pepper leaves and safflower buds) were analyzed for nucleotides by high performance liquid chromatography and for hexose and acid-soluble P—pepper was still vegetative whereas safflower had switched to flower bud formation—the salt stress reduced the fresh shoot yield of pepper by nearly two-thirds and of safflower by half. It reduced the ATP pool and ATP/ADP ratio in the source leaves of both species and also in the young pepper leaves. It had little or no effect on ATP or other nucleotide pools in safflower buds. The UDPG pool was not affected in source leaves or safflower buds, but in the young pepper leaves it was reduced by half, along with UTP. -
Non-Enzymatic Synthesis of the Coenzymes, Uridine Diphosphate
N O N - E N Z Y M A T I C S Y N T H E S I S OF THE C O E N Z Y M E S , U R I D I N E D I P H O S P H A T E G L U C O S E A N D C Y T I D I N E D I P H O S P H A T E C H O L I N E , A N D O T H E R P H O S P H O R Y L A T E D M E T A B O L I C I N T E R M E D I A T E S A. M A R , J. D W O R K I N , and J. ORO* Department of Biochemical and Biophysical Sciences, University of Houston, Houston, TX 77004, U.S.A. (Received 3 November, 1986) Abstract. The synthesis of uridine diphosphate glucose (UDPG), cytidine diphosphate choline (CDP- choline), glucose-l-phosphate (G1P) and glucose-6-phosphate (G6P) has been accomplished under simulated prebiotic conditions using urea and cyanamide, two condensing agents considered to have been present on the primitive Earth. The synthesis of UDPG was carried out by reacting G1P and UTP at 70 °C for 24 hours in the presence of the condensing agents in an aqueous medium. CDP-choline was obtained under the same conditions by reacting choline phosphate and CTP. G1P and G6P were synthesized from glucose and inorganic phosphate at 70°C for 16 hours.