Purine or pyrimidine bases attached to a ribose or deoxyribose. (From King & Stansfield, A Dictionary of Genetics, 4th ed)
Purines with a RIBOSE attached that can be phosphorylated to PURINE NUCLEOTIDES.
Pyrimidines with a RIBOSE attached that can be phosphorylated to PYRIMIDINE NUCLEOTIDES.
Nucleoside Transport Proteins
Equilibrative Nucleoside Transporter 1
Sulfhydryl analog of INOSINE that inhibits nucleoside transport across erythrocyte plasma membranes, and has immunosuppressive properties. It has been used similarly to MERCAPTOPURINE in the treatment of leukemia. (From Martindale, The Extra Pharmacopoeia, 30th ed, p503)
A purine nucleoside that has guanine linked by its N9 nitrogen to the C1 carbon of ribose. It is a component of ribonucleic acid and its nucleotides play important roles in metabolism. (From Dorland, 28th ed)
An enzyme that is found in mitochondria and in the soluble cytoplasm of cells. It catalyzes reversible reactions of a nucleoside triphosphate, e.g., ATP, with a nucleoside diphosphate, e.g., UDP, to form ADP and UTP. Many nucleoside diphosphates can act as acceptor, while many ribo- and deoxyribonucleoside triphosphates can act as donor. EC 220.127.116.11.
A purine nucleoside that has hypoxanthine linked by the N9 nitrogen to the C1 carbon of ribose. It is an intermediate in the degradation of purines and purine nucleosides to uric acid and in pathways of purine salvage. It also occurs in the anticodon of certain transfer RNA molecules. (Dorland, 28th ed)
A modified nucleoside which is present in the first position of the anticodon of tRNA-tyrosine, tRNA-histidine, tRNA-asparagine and tRNA-aspartic acid of many organisms. It is believed to play a role in the regulatory function of tRNA. Nucleoside Q can be further modified to nucleoside Q*, which has a mannose or galactose moiety linked to position 4 of its cyclopentenediol moiety.
Equilibrative-Nucleoside Transporter 2
An enzyme which catalyzes the hydrolysis of nucleoside triphosphates to nucleoside diphosphates. It may also catalyze the hydrolysis of nucleotide triphosphates, diphosphates, thiamine diphosphates and FAD. The nucleoside triphosphate phosphohydrolases I and II are subtypes of the enzyme which are found mostly in viruses.
A pyrimidine nucleoside that is composed of the base CYTOSINE linked to the five-carbon sugar D-RIBOSE.
Nucleosides in which the purine or pyrimidine base is combined with ribose. (Dorland, 28th ed)
Pyrazolopyrimidine ribonucleosides isolated from Nocardia interforma. They are antineoplastic antibiotics with cytostatic properties.
NM23 Nucleoside Diphosphate Kinases
A family of nucleotide diphosphate kinases that play a role in a variety of cellular signaling pathways that effect CELL DIFFERENTIATION; CELL PROLIFERATION; and APOPTOSIS. They are considered multifunctional proteins that interact with a variety of cellular proteins and have functions that are unrelated to their enzyme activity.
Reverse Transcriptase Inhibitors
Equilibrative Nucleoside Transport Proteins
A purine or pyrimidine base bonded to DEOXYRIBOSE.
Adenosine molecules which can be substituted in any position, but are lacking one hydroxyl group in the ribose part of the molecule.
A purine base and a fundamental unit of ADENINE NUCLEOTIDES.
Nucleosides that have two hydroxy groups removed from the sugar moiety. The majority of these compounds have broad-spectrum antiretroviral activity due to their action as antimetabolites. The nucleosides are phosphorylated intracellularly to their 5'-triphosphates and act as chain-terminating inhibitors of viral reverse transcription.
An antibiotic purine ribonucleoside that readily substitutes for adenosine in the biological system, but its incorporation into DNA and RNA has an inhibitory effect on the metabolism of these nucleic acids.
A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by an azido group. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. The compound is a potent inhibitor of HIV replication, acting as a chain-terminator of viral DNA during reverse transcription. It improves immunologic function, partially reverses the HIV-induced neurological dysfunction, and improves certain other clinical abnormalities associated with AIDS. Its principal toxic effect is dose-dependent suppression of bone marrow, resulting in anemia and leukopenia.
Agents used in the prophylaxis or therapy of VIRUS DISEASES. Some of the ways they may act include preventing viral replication by inhibiting viral DNA polymerase; binding to specific cell-surface receptors and inhibiting viral penetration or uncoating; inhibiting viral protein synthesis; or blocking late stages of virus assembly.
A series of heterocyclic compounds that are variously substituted in nature and are known also as purine bases. They include ADENINE and GUANINE, constituents of nucleic acids, as well as many alkaloids such as CAFFEINE and THEOPHYLLINE. Uric acid is the metabolic end product of purine metabolism.
An enzyme that catalyzes reversibly the phosphorylation of deoxycytidine with the formation of a nucleoside diphosphate and deoxycytidine monophosphate. Cytosine arabinoside can also act as an acceptor. All natural nucleoside triphosphates, except deoxycytidine triphosphate, can act as donors. The enzyme is induced by some viruses, particularly the herpes simplex virus (HERPESVIRUS HOMINIS). EC 18.104.22.168.
Nucleotides in which the purine or pyrimidine base is combined with ribose. (Dorland, 28th ed)
2'-Deoxyuridine. An antimetabolite that is converted to deoxyuridine triphosphate during DNA synthesis. Laboratory suppression of deoxyuridine is used to diagnose megaloblastic anemias due to vitamin B12 and folate deficiencies.
A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by a hydrogen. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. The compound is a potent inhibitor of HIV replication at low concentrations, acting as a chain-terminator of viral DNA by binding to reverse transcriptase. Its principal toxic side effect is axonal degeneration resulting in peripheral neuropathy.
A phosphodiesterase inhibitor that blocks uptake and metabolism of adenosine by erythrocytes and vascular endothelial cells. Dipyridamole also potentiates the antiaggregating action of prostacyclin. (From AMA Drug Evaluations Annual, 1994, p752)
HIV Reverse Transcriptase
A reverse transcriptase encoded by the POL GENE of HIV. It is a heterodimer of 66 kDa and 51 kDa subunits that are derived from a common precursor protein. The heterodimer also includes an RNAse H activity (RIBONUCLEASE H, HUMAN IMMUNODEFICIENCY VIRUS) that plays an essential role the viral replication process.
Phosphate esters of THYMIDINE in N-glycosidic linkage with ribose or deoxyribose, as occurs in nucleic acids. (From Dorland, 28th ed, p1154)
Acid Anhydride Hydrolases
A group of enzymes that catalyze the hydrolysis of diphosphate bonds in compounds such as nucleoside di- and tri-phosphates, and sulfonyl-containing anhydrides such as adenylylsulfate. (Enzyme Nomenclature, 1992) EC 3.6.
An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.
The phosphate esters of DIDEOXYNUCLEOSIDES.
Catalyze the hydrolysis of nucleosides with the elimination of ammonia.
A purine and a reaction intermediate in the metabolism of adenosine and in the formation of nucleic acids by the salvage pathway.
A nucleoside consisting of the base guanine and the sugar deoxyribose.
Molecular Sequence Data
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
A photoactivable URIDINE analog that is used as an affinity label.
Membrane Transport Proteins
Membrane proteins whose primary function is to facilitate the transport of molecules across a biological membrane. Included in this broad category are proteins involved in active transport (BIOLOGICAL TRANSPORT, ACTIVE), facilitated transport and ION CHANNELS.
Cytidine 5'-(tetrahydrogen triphosphate). A cytosine nucleotide containing three phosphate groups esterified to the sugar moiety.
Drug Resistance, Viral
The ability of viruses to resist or to become tolerant to chemotherapeutic agents or antiviral agents. This resistance is acquired through gene mutation.
A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by a hydrogen. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. Didanosine is a potent inhibitor of HIV replication, acting as a chain-terminator of viral DNA by binding to reverse transcriptase; ddI is then metabolized to dideoxyadenosine triphosphate, its putative active metabolite.
A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.
Purine bases related to hypoxanthine, an intermediate product of uric acid synthesis and a breakdown product of adenine catabolism.
A purine or pyrimidine base bonded to a DEOXYRIBOSE containing a bond to a phosphate group.
A group of enzymes within the class EC 3.6.1.- that catalyze the hydrolysis of diphosphate bonds, chiefly in nucleoside di- and triphosphates. They may liberate either a mono- or diphosphate. EC 3.6.1.-.
A pyrimidine nucleoside formed in the body by the deamination of CYTARABINE.
Adenosine Deaminase Inhibitors
Drugs that inhibit ADENOSINE DEAMINASE activity.
Guanine nucleotides which contain deoxyribose as the sugar moiety.
The small RNA molecules, 73-80 nucleotides long, that function during translation (TRANSLATION, GENETIC) to align AMINO ACIDS at the RIBOSOMES in a sequence determined by the mRNA (RNA, MESSENGER). There are about 30 different transfer RNAs. Each recognizes a specific CODON set on the mRNA through its own ANTICODON and as aminoacyl tRNAs (RNA, TRANSFER, AMINO ACYL), each carries a specific amino acid to the ribosome to add to the elongating peptide chains.
An enzyme that catalyzes the formation of ADP plus AMP from adenosine plus ATP. It can serve as a salvage mechanism for returning adenosine to nucleic acids. EC 22.214.171.124.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
An enzyme that catalyzes the conversion of ATP and thymidine to ADP and thymidine 5'-phosphate. Deoxyuridine can also act as an acceptor and dGTP as a donor. (From Enzyme Nomenclature, 1992) EC 126.96.36.199.
A calcium-activated enzyme that catalyzes the hydrolysis of ATP to yield AMP and orthophosphate. It can also act on ADP and other nucleoside triphosphates and diphosphates. EC 188.8.131.52.
A reverse transcriptase inhibitor and ZALCITABINE analog in which a sulfur atom replaces the 3' carbon of the pentose ring. It is used to treat HIV disease.
A pyrimidine base that is a fundamental unit of nucleic acids.
An antineoplastic antimetabolite that is metabolized to fluorouracil when administered by rapid injection; when administered by slow, continuous, intra-arterial infusion, it is converted to floxuridine monophosphate. It has been used to treat hepatic metastases of gastrointestinal adenocarcinomas and for palliation in malignant neoplasms of the liver and gastrointestinal tract.
A glycoprotein enzyme present in various organs and in many cells. The enzyme catalyzes the hydrolysis of a 5'-ribonucleotide to a ribonucleoside and orthophosphate in the presence of water. It is cation-dependent and exists in a membrane-bound and soluble form. EC 184.108.40.206.
Amino Acid Sequence
Guanosine 5'-(tetrahydrogen triphosphate). A guanine nucleotide containing three phosphate groups esterified to the sugar moiety.
Polymers made up of a few (2-20) nucleotides. In molecular genetics, they refer to a short sequence synthesized to match a region where a mutation is known to occur, and then used as a probe (OLIGONUCLEOTIDE PROBES). (Dorland, 28th ed)
A GUANOSINE analog that acts as an antimetabolite. Viruses are especially susceptible. Used especially against herpes.
Chromatography, High Pressure Liquid
6-(Methylthio)-9-beta-D-ribofuranosylpurine. An analog of inosine with a methylthio group replacing the hydroxyl group in the 6-position.
A guanine nucleotide containing one phosphate group esterified to the sugar moiety and found widely in nature.
A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)
Magnetic Resonance Spectroscopy
A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).
Phosphoric Monoester Hydrolases
A group of hydrolases which catalyze the hydrolysis of monophosphoric esters with the production of one mole of orthophosphate. EC 3.1.3.
An enzyme that catalyzes the hydrolysis of ADENOSINE to INOSINE with the elimination of AMMONIA.
A nucleoside antibiotic isolated from Streptomyces antibioticus. It has some antineoplastic properties and has broad spectrum activity against DNA viruses in cell cultures and significant antiviral activity against infections caused by a variety of viruses such as the herpes viruses, the VACCINIA VIRUS and varicella zoster virus.
An adenosine monophosphate analog in which ribose is replaced by an arabinose moiety. It is the monophosphate ester of VIDARABINE with antiviral and possibly antineoplastic properties.
N(6)-[delta(3)-isopentenyl]adenosine. Isopentenyl derivative of adenosine which is a member of the cytokinin family of plant growth regulators.
A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by a hydrogen. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. The compound is an inhibitor of HIV replication, acting as a chain-terminator of viral DNA by binding to reverse transcriptase. Its principal side effect is nephrotoxicity. In vivo, dideoxyadenosine is rapidly metabolized to DIDANOSINE (ddI) by enzymatic deamination; ddI is then converted to dideoxyinosine monophosphate and ultimately to dideoxyadenosine triphosphate, the putative active metabolite.
An active blood parasite that is present in practically all domestic animals in Africa, the West Indies, and parts of Central and South America. In Africa, the insect vector is the tsetse fly. In other countries, infection is by mechanical means indicating that the parasites have been introduced to these countries and have been able to maintain themselves in spite of the lack of a suitable intermediate host. It is a cause of nagana, the severity of which depends on the species affected.
A pyrimidine nucleoside analog that is used mainly in the treatment of leukemia, especially acute non-lymphoblastic leukemia. Cytarabine is an antimetabolite antineoplastic agent that inhibits the synthesis of DNA. Its actions are specific for the S phase of the cell cycle. It also has antiviral and immunosuppressant properties. (From Martindale, The Extra Pharmacopoeia, 30th ed, p472)
5'-Uridylic acid. A uracil nucleotide containing one phosphate group esterified to the sugar moiety in the 2', 3' or 5' position.
The sequential set of three nucleotides in TRANSFER RNA that interacts with its complement in MESSENGER RNA, the CODON, during translation in the ribosome.
A class of enzymes involved in the hydrolysis of the N-glycosidic bond of nitrogen-linked sugars.
An enzyme which catalyzes the catabolism of S-ADENOSYLHOMOCYSTEINE to ADENOSINE and HOMOCYSTEINE. It may play a role in regulating the concentration of intracellular adenosylhomocysteine.
A group of compounds which consist of a nucleotide molecule to which an additional nucleoside is attached through the phosphate molecule(s). The nucleotide can contain any number of phosphates.
Nucleoside Diphosphate Kinase D
Nucleobase Transport Proteins
Proteins involved in the transport of nucleobases such as PYRIMIDINES and PURINES across membranes.
A potent inhibitor of ADENOSINE DEAMINASE. The drug induces APOPTOSIS of LYMPHOCYTES, and is used in the treatment of many lymphoproliferative malignancies, particularly HAIRY CELL LEUKEMIA. It is also synergistic with some other antineoplastic agents and has immunosuppressive activity.
High molecular weight polymers containing a mixture of purine and pyrimidine nucleotides chained together by ribose or deoxyribose linkages.
Adenosine 5'-(trihydrogen diphosphate). An adenine nucleotide containing two phosphate groups esterified to the sugar moiety at the 5'-position.
Proteins prepared by recombinant DNA technology.
Adenine nucleotides which contain deoxyribose as the sugar moiety.
Nucleic Acid Conformation
Cytidine (dihydrogen phosphate). A cytosine nucleotide containing one phosphate group esterified to the sugar moiety in the 2', 3' or 5' position.
Uridine 5'-(tetrahydrogen triphosphate). A uracil nucleotide containing three phosphate groups esterified to the sugar moiety.
Indicators and Reagents
Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499)
The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.
A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.
Inosine 5'-Monophosphate. A purine nucleotide which has hypoxanthine as the base and one phosphate group esterified to the sugar moiety.
A group of deoxyribonucleotides (up to 12) in which the phosphate residues of each deoxyribonucleotide act as bridges in forming diester linkages between the deoxyribose moieties.
An ACYCLOVIR analog that is a potent inhibitor of the Herpesvirus family including cytomegalovirus. Ganciclovir is used to treat complications from AIDS-associated cytomegalovirus infections.
The process of intracellular viral multiplication, consisting of the synthesis of PROTEINS; NUCLEIC ACIDS; and sometimes LIPIDS, and their assembly into a new infectious particle.
Drug Resistance, Multiple, Viral
The ability of viruses to resist or to become tolerant to several structurally and functionally distinct drugs simultaneously. This resistance phenotype may be attributed to multiple gene mutation.
A ribonucleoside antibiotic synergist and adenosine deaminase inhibitor isolated from Nocardia interforma and Streptomyces kaniharaensis. It is proposed as an antineoplastic synergist and immunosuppressant.
HIV Protease Inhibitors
5-Thymidylic acid. A thymine nucleotide containing one phosphate group esterified to the deoxyribose moiety.
DNA-Directed DNA Polymerase
DNA-dependent DNA polymerases found in bacteria, animal and plant cells. During the replication process, these enzymes catalyze the addition of deoxyribonucleotide residues to the end of a DNA strand in the presence of DNA as template-primer. They also possess exonuclease activity and therefore function in DNA repair.
Adenosine A3 Receptor Agonists
Drugs that selectively bind to and activate ADENOSINE A3 RECEPTORS.
A group of ribonucleotides (up to 12) in which the phosphate residues of each ribonucleotide act as bridges in forming diester linkages between the ribose moieties.
Nucleobase, Nucleoside, Nucleotide, and Nucleic Acid Transport Proteins
A broad class of proteins involved in the transport of nucleobases, NUCLEOSIDES; NUCLEOTIDES; and NUCLEIC ACIDS; across membranes.
Sequence Homology, Amino Acid
Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.
A uracil nucleotide containing a pyrophosphate group esterified to C5 of the sugar moiety.
Inosine 5'-(tetrahydrogen triphosphate). An inosine nucleotide containing three phosphate groups esterified to the sugar moiety. Synonym: IRPPP.
Receptor, Adenosine A3
A subtype of ADENOSINE RECEPTOR that is found expressed in a variety of locations including the BRAIN and endocrine tissues. The receptor is generally considered to be coupled to the GI, INHIBITORY G-PROTEIN which causes down regulation of CYCLIC AMP.
Chromatography, Thin Layer
Dose-Response Relationship, Drug
An enzyme that catalyzes the deamination of guanine to form xanthine. EC 220.127.116.11.
A purine that is an isomer of ADENINE (6-aminopurine).
An antiviral derivative of THYMIDINE used mainly in the treatment of primary keratoconjunctivitis and recurrent epithelial keratitis due to HERPES SIMPLEX virus. (From Martindale, The Extra Pharmacopoeia, 30th ed, p557)