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Searched for: HUMANCYC AND pyrimidine deoxyribonucleotides de novo biosynthesis [All Organisms, All Data Sources]

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Pathways (9)Molecules (6)
Showing Results 1 - 9 of 9 
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Pathway: pyrimidine deoxyribonucleotides de novo biosynthesis  from HumanCyc  [44 molecules]
  • ... HUMANCYC ...
  • Nucleoside diphosphate kinase 7 ...
  • ... pyrimidine deoxyribonucleotides [Cont. ...] de novo biosynthesis ...
  • ... HumanCyc ...
  • ... deoxypyrimidine nucleotide/nucleoside metabolism ...
  • DCTP-DEAM-RXN ...
  • Deoxycytidine triphosphate deaminase ...
  • ... dCTP deaminase ...
  • Desoxyuridine 5'-triphosphatase ...
  • Desoxyuridine 5 ...
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Pathway: uridine-5'-phosphate biosynthesis  from HumanCyc  [22 molecules]
General Background The pyrimidine and purine nucleotides essential components of nucleic acids, and.

Summary:  General Background The pyrimidine and purine nucleotides essential components of nucleic acids, and.play a crucial role in growth, development and reproduction, as well as in a large number of essential metabolic progressions such as interconversions from sugars to polysaccharides, glycoproteins and phospholipids. The de novo biosynthesis of pyrimidine nucleotides appears to be one of the most ancient biochemical pathways as it is evolutionary conserved in all species. Although the enzymatic steps in this pathway are conserved throughout all organisms, some differences in the enzymes do exist. For example, in plants and bacteria the three steps leading from |FRAME: CARBAMOYL-P| to |FRAME: OROTATE| are catalyzed by three different proteins, while in mammals they are catalyzed by the single multifunctional |FRAME: CPLX-6703| |CITS: [8619816]|. The last two steps of the pathway are carried out by a bi-functional enzyme (|FRAME: AT3G54470-MONOMER|) in plants and animals, whereas bacteria express two separate proteins for that purpose. About This Pathway The de novo pyrimidine nucleotide biosynthetic pathway converts |FRAME: HCO3|, |FRAME: GLN|, |FRAME: L-ASPARTATE| and |FRAME: PRPP| (PRPP) to |FRAME: UMP| (UMP), a pyrimidine that can be subsequently converted to other pyrimidines (see |FRAME: PWY-5687|). The first enzyme, |FRAME: CARBPSYN-CPLX|, forms |FRAME: CARBAMOYL-P| which is not only an intermediate of pyrimidine synthesis but also a precursor for the synthesis of amino acids such as |FRAME: ARG|, |FRAME: L-CITRULLINE| and |FRAME: CANAVANINE|. The next step is the condensation of |FRAME: CARBAMOYL-P| with |FRAME: L-ASPARTATE| forming |FRAME: CARBAMYUL-L-ASPARTATE|, which is cyclized to |FRAME: DI-H-OROTATE|, the first intermediate that contains a pyrimidine ring. |FRAME: DI-H-OROTATE| is oxidized to |FRAME: OROTATE| by |FRAME:DIHYDROOROTOX-ENZRXN|. The final two steps, the condensation of |FRAME: OROTATE| with PRPP forming |FRAME: OROTIDINE-5-PHOSPHATE| (OMP) followed by the decarboylation of OMP to UMP, are carried out by the enzyme |FRAME: OROTPDECARB-CPLX|. The last step is considered as the rate-limiting step of the overall de novo biosynthesis of pyrimidine nucleotides.

  • ... HUMANCYC ...
  • ... pyrimidine biosynthesis ...
  • ... ide novo/i biosynthesis of uridine-5'-phosphate ...
  • ... ide novo/i biosynthesis of uridine-5'-monophosphate ...
  • ... uridine-5'-phosphate biosynthesis ...
  • ... HumanCyc ...
  • ... bGeneral Background/b The pyrimidine and purine nucleotides. ... to polysaccharides, glycoproteins and phospholipids. ... The ide novo/i biosynthesis of pyrimidine. ... of the overall ide novo/i biosynthesis of pyrimidine nucleotides.
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Pathway: pyrimidine ribonucleotides de novo biosynthesis  from HumanCyc  [36 molecules]
  • ... for de novo pyrimidine biosynthesis |CITS:[11125071]| ...
  • ... HUMANCYC 271828.
  • ... pyrimidine ribonucleotides de novo biosynthesis ...
  • ... HumanCyc ...
  • ... monophosphate decarboxylase activities; required for de novo pyrimidine biosynthesis |CITS. ... activities; required for de novo pyrimidine biosynthesis |CITS:[11125071]| ...
  • OROTPDECARB-RXN 271828. ... and orotidine monophosphate decarboxylase activities; required for de novo pyrimidine biosynthesis ...
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Pathway: pyrimidine ribonucleotides interconversion  from HumanCyc  [22 molecules]
General Background Pyrimidine and purine nucleotides represent fundamental compounds central to both primary metabolism and many aspects of secondary metabolism.

Summary:  General Background Pyrimidine and purine nucleotides represent fundamental compounds central to both primary metabolism and many aspects of secondary metabolism. Involved in many cellular processes, pyrimidines are considered of vital importance for growth, development and reproduction. The de novo biosynthesis of pyrimidine ribonucleotides gives rise to |FRAME: UMP| (UMP) from which all other pyrimidines within the cell are derived. Further phosphotransfer and nucleotide modification reactions (illustrated in this pathway) convert the monophosphate to diphosphate and triphosphate nucleotides. |FRAME: UDP| is of special importance as it serves as a glycosyl carrier in a plethora of reactions involved in many primary and secondary metabolism pathways. About This Pathway The pyrimidine nucleotide metabolism enclosing phosphotransfer and nucleotide modification routes appears to connect to a network of interacting metabolic pathways involved in growth and development which is not well understood. The first enzyme of the pathway, catalyzes the phosphorylation of UMP to form UDP. The conserved glycine-rich sequence GGPG(S/A)GK, a hallmark for all eukaryotic monophosphokinases, has been found of significant importance for ATP binding and enzyme catalysis. The next enzyme in the pathway, |FRAME: NUCLEOSIDE-DIP-KIN-CPLX| (NDK), catalyzes a reaction in which the terminal phosphate of a nucleoside-triphosphate is transferred to a nucleoside-diphosphate - in this case, the transfer of a phosphate from ATP to UDP, forming UTP. The enzyme has a broad substrate specificity, and is involved in the biosynthesis of several nucleoside-triphosphates, including formation of CTP from CDP. Interconversion between thymidine and cytidine nucleosides is made possible by the glutamine (or ammonia)-dependent enzyme |FRAME: CTPSYN-CPLX|.

  • ... HUMANCYC ...
  • ... pyrimidine biosynthesis ...
  • ... HUMANCYC 271828.
  • ... pyrimidine ribonucleotides interconversion ...
  • ... HumanCyc ...
  • ... are considered of vital importance for growth, development and reproduction. ... The ide novo/i biosynthesis.
  • ... HUMANCYC 271828 ...
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Pathway: salvage pathways of pyrimidine deoxyribonucleotides  from HumanCyc  [19 molecules]
  • ... salvage pathways of pyrimidine deoxyribonucleotides [Cont. ...] ...
  • ... HumanCyc ...
  • ... HUMANCYC ...
  • ... deoxypyrimidine nucleotide/nucleoside metabolism ...
  • ... Pyrimidine phosphorylase ...
  • ... HUMANCYC. ... HUMANCYC ...
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Pathway: tetrahydrofolate salvage from 5,10-methenyltetrahydrofolate  from HumanCyc  [16 molecules]
General Background Tetrahydrofolate (vitamin B9) and its derivatives, commonly termed folates, are essential cofactors that facilitate the transfer of one-carbon units from donor molecules into important biosynthetic pathways leading to methionine, purine, and pyrimidine biosynthesis.

Summary:  General Background Tetrahydrofolate (vitamin B9) and its derivatives, commonly termed folates, are essential cofactors that facilitate the transfer of one-carbon units from donor molecules into important biosynthetic pathways leading to methionine, purine, and pyrimidine biosynthesis. Folates also mediate the interconversion of serine and glycine, play a role in histidine catabolism |CITS: [11001804]|, and in plants are also involved in photorespiration, amino acid metabolism and chloroplastic protein biosynthesis |CITS: [11960743]| |CITS: [12644692]|. Folates are abundant in green leaves, and folic acid was initially isolated from a large amount (four tons) of spinach leaves. The name folate is derived from the Latin folium (leaf) |CITS: [3067148]|. Folates are modified by the addition of glutamate moieties conjugated one to another via a series of γ-glutamyl links to form an oligo-γ-glutamyl tail. The polyglutamylated forms are usually preferred by the enzymes that use folates since the turnover rate of those compounds is markedly increased |CITS: [9190084][SCOTT00][KIRK94]|. In addition, in eukaryotic cells the glutamylated forms of folate facilitate the retention of the vitamin within the cell and its subcellular compartments |CITS: [1916088]|. |FRAME: THF Tetrahydrofolate| (tetrahydropteroylmonoglutamate, H4PteGlu1, THF) is merely the parent structure of this large family of coenzymes. Members of the family differ in the oxidation state of the pteridine ring, the character of the one-carbon substituent at the N5 and N10 positions (see |FRAME: PWY-2201 folate transformations I|), and the number of conjugated glutamate residues (see |FRAME: PWY-2161 folate polyglutamylation|). About This Pathway While plants and many microorganisms can synthesize folate coenzymes by the de novo synthesis pathway (see |FRAME: PWY-6612 superpathway of tetrahydrofolate biosynthesis|), many of them are also capable of salvaging folate from different varieties, such as the 5,10-methenyl form, or the 5- or 10-formyl forms. This pathway describes the conversion of pre-existing |FRAME: METHYLENE-THF 5,10-methylenetetrahydrofolate| and |FRAME:10-FORMYL-THF 10-formyl-tetrahydrofolate| to |FRAME: THF tetrahydrofolate|. As vertebrates are not able to synthesize folate in vivo, they are absolutely dependent on nutritional sources, making folate a vitamin. Food folates exist mainly as the polyglutamylated forms |FRAME: 5-METHYL-THF 5-methyl-tetrahydrofolate| and |FRAME: 10-FORMYL-THF 10-formyl-tetrahydrofolate| (formyl-H4PteGlun) |CITS: [405403]|. The polyglutamyl folates are hydrolyzed to monoglutamate forms by |FRAME: MONOMER-5321 γ-glutamyl hydrolase|, and metabolized 5-methyl-H4PteGlu1. More about that process is found at the pathway |FRAME: PWY-2161B glutamate removal from folates|. Insufficient supply of the vitamin in vertebrates leads to anemia in adults, and has been shown to cause neural tube malformation in human embryos |CITS: [11744531]|. In addition, folate defficiency has been linked to a number of other birth defects, several types of cancer, dementia, affective disorders, Down's syndrom, and serious conditions affecting pregnancy outcome (for a review, see |CITS: [11001804]|).

  • ... , phosphoribosylaminoimidazole synthetase activity which is required for de novo purine biosynthesis.
  • ... De novo.
  • Cloning of three human multifunctional de novo purine biosynthetic genes. ... synthetase, phosphoribosylglycinamide formyltransferase and synthetase activity; required for de novo purine. ..., and pyrimidine biosynthesis.
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Pathway: purine nucleotides degradation II (aerobic)  from HumanCyc  [37 molecules]
General Background The pathways of biosynthesis and degradation of mammalian purine and pyrimidine bases, nucleosides and nucleotides were elucidated in the 1950s and 1960s.

Summary:  General Background The pathways of biosynthesis and degradation of mammalian purine and pyrimidine bases, nucleosides and nucleotides were elucidated in the 1950s and 1960s. Much work in the 1970s and 1980s focused on inborn errors of purine metabolism, although the regulation of purine nucleotide synthesis and the metabolism of purine bases and nucleosides were also studied. More recent work on purine and pyrimidine metabolism using genomics, proteiomics and metabolomics is likely to impact several areas of clinical research including studies of a possible role for high levels of soluble urate in cardiovascular diseases; the development of purine and pyrimidine analogs for the chemotherapy of cancer and autoimmune diseases as well for antiviral and antiparasitic drugs; and the development of urate-lowering drugs for the treatment of gout. Reviewed in |CITS: [18600501]| and |CITS: [16176880]|. About This Pathway In mammals both purine ribonucleotide and purine deoxyribonucleotide monophosphates are degraded similarly using a final common pathway. The degradation reactions of purine ribonucleotide monophosphates are shown here as in |CITS: [6262603] [17520339] [1576959]| and |CITS: [11150394]|. Purine degradation in higher plants is shown in |FRAME: PWY-5044|. Related pathways of eukaryotic purine de novo biosynthesis and purine salvage (reutilization) are shown in pathways |FRAME: PWY-841|, |FRAME: SALVADEHYPOX-PWY| and |FRAME: SALVPURINE2-PWY|. Rodent studues have demonstrated the catabolism of dietary purines by epithelial cells lining the gastrointestinal tract. These cells coexpress key purine catabolic enzymes |CITS: [1918135]| . The first step in degradation involves hydrolysis of purine ribonucleotides to ribonucleosides by 5'-nucleotidase (EC 3.1.3.5). As stated in |CITS: [6262603]| this step can also be catalyzed by non-specific phosphatases such as EC 3.1.3.2 (not shown). |FRAME: AMP| is deaminated to |FRAME: IMP| (EC 3.5.4.6). Ribonucleosides are converted to purine bases and |FRAME: RIBOSE-1P| by phosphorolysis catalyzed by purine nucleoside phosphorylase (EC 2.4.2.1). |FRAME: ADENOSINE| is deaminated to |FRAME: INOSINE| (EC 3.5.4.4), and |FRAME: GUANINE| is deaminated to |FRAME: XANTHINE| (EC 3.5.4.3). |FRAME: HYPOXANTHINE| is converted to |FRAME: XANTHINE|, which is then converted to |FRAME: URATE| by the same enzyme, xanthine oxidoreductase (xanthine dehydrogenase EC 1.17.1.4, xanthine oxidase EC 1.17.3.2). This is the rate-limiting enzyme in the pathway. Reviewed in |CITS: [6262603] [18513323]| and |CITS: [19436671]|). Also shown in this pathway is the degradation of |FRAME: XANTHOSINE-5-PHOSPHATE|, an intermediate in the biosynthesis of |FRAME: GMP| from |FRAME: IMP| (see pathway |FRAME: PWY-841|). |FRAME: XANTHOSINE-5-PHOSPHATE| degradation is included in some pathway diagrams |CITS: [1576959] [VOET04]|. |FRAME: XANTHOSINE-5-PHOSPHATE| has been shown to be a substrate for 5'-nucleotidase EC 3.1.3.5 (reviewed in |CITS: [15963349]|). |FRAME: XANTHOSINE|, in addition to |FRAME: GUANOSINE| and |FRAME: INOSINE|, is also a substrate for phosphorolysis by purine nucleoside phosphorylase EC 2.4.2.1 |CITS: [12180982]| and reviewed in |CITS: [15218545]|. Unlike the prokaryotic enzyme, |FRAME: ADENOSINE| is not a natural substrate for mammalian purine nucleoside phosphorylase (in |CITS: [12180982]|). The end product of purine catabolism depends upon the taxon of the organism in question. |FRAME: URATE| is the end product in humans, hominoid primates (i.e. chimpanzees, gorillas), new world monkeys, birds and reptiles. Higher primates contain a mutational inactivation of the liver enzyme uricase and cannot produce |FRAME: ALLANTOIN|. |FRAME: ALLANTOIN| is produced in non-primate mammals and old world monkeys, which produce uricase (see linked pathway |FRAME: PWY-5691|). Other organisms can also produce and further catabolize |FRAME: ALLANTOIN| (see the pathway link in |FRAME: PWY-5691| and subsequent links). In |CITS: [18649082]| and in |CITS: [15919000]|. In humans, |FRAME: URATE| in blood enters the kidney but most is reabsorbed by a renal |FRAME: URATE| reabsorption system. Only approximately 10% is excreted. Kidney |FRAME: URATE| transporting systems are still under investigation. Both |FRAME: URATE| and |FRAME: ALLANTOIN| are found in the urine of species that produce them (reviewed in |CITS: [15919000]|). Abnormalities of the human pathway occur as a result of enzyme deficiencies, enzyme overactivities, and increased turnover of nucleic acids due to certain disorders. Conditions resulting in increased degradation of |FRAME: ATP|, or decreased synthesis of |FRAME: ATP|, also affect purine nucleotide degradation. After purine nucleotide dephosphorylation, the salvage (reutilization) reactions may be a major regulatory mechanism (reviewed in |CITS: [6262603]|) (see pathways |FRAME: SALVADEHYPOX-PWY| and |FRAME: SALVPURINE2-PWY|). The enzymes of the pathway occur in a variety of mammalian tissues. In mice the highest levels of purine catabolic enzymes have been found in the proximal small intestine |CITS: [8226898]|.

  • ... HUMANCYC ...
  • ... purine nucleotides catabolism ...
  • ... xanthine dehydrogenase ...
  • ... HumanCyc ...
  • ... bGeneral Background/b The pathways of biosynthesis and degradation of mammalian purine and pyrimidine bases, nucleosides. ... of purine bases and nucleosides were also studied. ... More recent work on purine and pyrimidine ...
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Pathway: salvage pathways of pyrimidine ribonucleotides  from HumanCyc  [34 molecules]
  • ... HUMANCYC ...
  • ... pyrimidine ribonucleotide/ribonucleoside< [Cont. ...] metabolism ...
  • ... HUMANCYC 271828. ... salvage pathways of pyrimidine ribonucleotides ...
  • ... HumanCyc ...
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Pathway: uracil degradation II (reductive)  from HumanCyc  [13 molecules]
General Background Pyrimidines can be catabolized through two different pathways.

Summary:  General Background Pyrimidines can be catabolized through two different pathways. This pathway and |FRAME: PWY-6430 thymine degradation|) in which pyrimidines are reduced to β-amino acids, |FRAME: CARBON-DIOXIDE CO2| and |FRAME: AMMONIA ammonia|. About This Pathway The reductive pathway of uracil is essentially the same in bacteria and mammalian tissues |CITS: [12981074][13428755]|. The product of the pathway, |FRAME: B-ALANINE β-alanine|, is a central component of |FRAME:PANTOTHENATE (R)-pantothenate| and |FRAME:GAMMA-BUTYROBETAINE γ-butyrobetaine| biosynthesis, and in mammals also functions as a neurotransmitter |CITS: [6117607]| and as a precursor for the biosynthesis of |FRAME: CARNOSINE carnosine| and |FRAME: CPD-401 anserine| |CITS: [3108250]|. it is generally thought that the pyrimidine degradation pathway is the main route for the synthesis of |FRAME: B-ALANINE β-alanine| in mammals |CITS: [14705962]|. The pathway proceeds in three sequential enzymatic steps. The first enzyme is |FRAME: HS06975-MONOMER dihydropyrimidine dehydrogenase| (EC 1.3.1.2), which catalyzes the reversible reduction of both |FRAME:URACIL uracil| and |FRAME: THYMINE thymine| to |FRAME: DI-H-URACIL 5,6-dihydrouracil| and |FRAME: DIHYDRO-THYMINE 5,6-dihydrothymine|, respectively. The second enzyme, |FRAME: HS07460-MONOMER dihydropyrimidinase| (EC 3.5.2.2) performs reversible hydrolytic ring-opening of |FRAME: DI-H-URACIL 5,6-dihydrouracil| and |FRAME: DIHYDRO-THYMINE 5,6-dihydrothymine| to |FRAME: 3-UREIDO-PROPIONATE 3-ureidopropionate| and |FRAME: 3-UREIDO-ISOBUTYRATE 3-ureido-isobutyrate|, respectively. Finally, |FRAME: HS01953-MONOMER β-ureidopropionase| (EC 3.5.1.6) catalyzes the irreversible hydrolysis of |FRAME: 3-UREIDO-PROPIONATE 3-ureidopropionate| and |FRAME: 3-UREIDO-ISOBUTYRATE 3-ureido-isobutyrate| to |FRAME: B-ALANINE β-alanine| and |FRAME: 3-AMINO-ISOBUTYRATE 3-amino-isobutyrate|, respectively, in a reaction that produces ammonium and carbon dioxide. This pathway has special importance in humans, since it is responsible for the degradation of |FRAME: CPD0-1327 5-fluorouracil|, an important anticancer drug. Patients with defects in the enzymes of this pathway show adverse response to treatment with this drug, including death |CITS: [993199]|.

  • ... HUMANCYC ...
  • ... β-alanine biosynthesis ...
  • ... pyrimidine hydrase ...
  • ... hydropyrimidine hydrase ...