Hypoxanthine: A purine and a reaction intermediate in the metabolism of adenosine and in the formation of nucleic acids by the salvage pathway.Hypoxanthines: Purine bases related to hypoxanthine, an intermediate product of uric acid synthesis and a breakdown product of adenine catabolism.Hypoxanthine Phosphoribosyltransferase: An enzyme that catalyzes the conversion of 5-phosphoribosyl-1-pyrophosphate and hypoxanthine, guanine, or 6-mercaptopurine to the corresponding 5'-mononucleotides and pyrophosphate. The enzyme is important in purine biosynthesis as well as central nervous system functions. Complete lack of enzyme activity is associated with the LESCH-NYHAN SYNDROME, while partial deficiency results in overproduction of uric acid. EC 2.4.2.8.Inosine: 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)Xanthine: A purine base found in most body tissues and fluids, certain plants, and some urinary calculi. It is an intermediate in the degradation of adenosine monophosphate to uric acid, being formed by oxidation of hypoxanthine. The methylated xanthine compounds caffeine, theobromine, and theophylline and their derivatives are used in medicine for their bronchodilator effects. (Dorland, 28th ed)Purines: 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.Inosine Monophosphate: Inosine 5'-Monophosphate. A purine nucleotide which has hypoxanthine as the base and one phosphate group esterified to the sugar moiety.Xanthine Oxidase: An iron-molybdenum flavoprotein containing FLAVIN-ADENINE DINUCLEOTIDE that oxidizes hypoxanthine, some other purines and pterins, and aldehydes. Deficiency of the enzyme, an autosomal recessive trait, causes xanthinuria.Phosphoribosyl Pyrophosphate: The key substance in the biosynthesis of histidine, tryptophan, and purine and pyrimidine nucleotides.Inosine NucleotidesAzaguanine: One of the early purine analogs showing antineoplastic activity. It functions as an antimetabolite and is easily incorporated into ribonucleic acids.Lesch-Nyhan Syndrome: An inherited disorder transmitted as a sex-linked trait and caused by a deficiency of an enzyme of purine metabolism; HYPOXANTHINE PHOSPHORIBOSYLTRANSFERASE. Affected individuals are normal in the first year of life and then develop psychomotor retardation, extrapyramidal movement disorders, progressive spasticity, and seizures. Self-destructive behaviors such as biting of fingers and lips are seen frequently. Intellectual impairment may also occur but is typically not severe. Elevation of uric acid in the serum leads to the development of renal calculi and gouty arthritis. (Menkes, Textbook of Child Neurology, 5th ed, pp127)Pentosyltransferases: Enzymes of the transferase class that catalyze the transfer of a pentose group from one compound to another.Adenine: A purine base and a fundamental unit of ADENINE NUCLEOTIDES.Xanthines: Purine bases found in body tissues and fluids and in some plants.Purine Nucleotides: Purines attached to a RIBOSE and a phosphate that can polymerize to form DNA and RNA.Purine-Nucleoside Phosphorylase: An enzyme that catalyzes the reaction between a purine nucleoside and orthophosphate to form a free purine plus ribose-5-phosphate. EC 2.4.2.1.Nucleobase Transport Proteins: Proteins involved in the transport of nucleobases such as PYRIMIDINES and PURINES across membranes.Uric Acid: An oxidation product, via XANTHINE OXIDASE, of oxypurines such as XANTHINE and HYPOXANTHINE. It is the final oxidation product of purine catabolism in humans and primates, whereas in most other mammals URATE OXIDASE further oxidizes it to ALLANTOIN.GuanineAdenine Phosphoribosyltransferase: An enzyme catalyzing the formation of AMP from adenine and phosphoribosylpyrophosphate. It can act as a salvage enzyme for recycling of adenine into nucleic acids. EC 2.4.2.7.Purine-Pyrimidine Metabolism, Inborn ErrorsAllopurinol: A XANTHINE OXIDASE inhibitor that decreases URIC ACID production. It also acts as an antimetabolite on some simpler organisms.Thioguanine: An antineoplastic compound which also has antimetabolite action. The drug is used in the therapy of acute leukemia.Adenosine: A nucleoside that is composed of ADENINE and D-RIBOSE. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter.Nucleosides: Purine or pyrimidine bases attached to a ribose or deoxyribose. (From King & Stansfield, A Dictionary of Genetics, 4th ed)Purine Nucleosides: Purines with a RIBOSE attached that can be phosphorylated to PURINE NUCLEOTIDES.Thioinosine: 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)Adenine NucleotidesXanthine Dehydrogenase: An enzyme that catalyzes the oxidation of XANTHINE in the presence of NAD+ to form URIC ACID and NADH. It acts also on a variety of other purines and aldehydes.Allantoin: A urea hydantoin that is found in URINE and PLANTS and is used in dermatological preparations.Guanosine Monophosphate: A guanine nucleotide containing one phosphate group esterified to the sugar moiety and found widely in nature.6-Mercaptopurine: An antimetabolite antineoplastic agent with immunosuppressant properties. It interferes with nucleic acid synthesis by inhibiting purine metabolism and is used, usually in combination with other drugs, in the treatment of or in remission maintenance programs for leukemia.Hybrid Cells: Any cell, other than a ZYGOTE, that contains elements (such as NUCLEI and CYTOPLASM) from two or more different cells, usually produced by artificial CELL FUSION.Kinetics: The rate dynamics in chemical or physical systems.Nucleoside Transport Proteins: Proteins involved in the transport of NUCLEOSIDES across cellular membranes.UracilAzaserine: Antibiotic substance produced by various Streptomyces species. It is an inhibitor of enzymatic activities that involve glutamine and is used as an antineoplastic and immunosuppressive agent.Archaeoglobales: An order of extremely thermophilic, sulfate-reducing archaea, in the kingdom EURYARCHAEOTA. The single family Archaeoglobaceae contains one genus ARCHAEOGLOBUS.Ribonucleosides: Nucleosides in which the purine or pyrimidine base is combined with ribose. (Dorland, 28th ed)Deamination: The removal of an amino group (NH2) from a chemical compound.Methylthioinosine: 6-(Methylthio)-9-beta-D-ribofuranosylpurine. An analog of inosine with a methylthio group replacing the hydroxyl group in the 6-position.Aminopterin: A folic acid derivative used as a rodenticide that has been shown to be teratogenic.Oxypurinol: A xanthine oxidase inhibitor.Adenosine Monophosphate: Adenine nucleotide containing one phosphate group esterified to the sugar moiety in the 2'-, 3'-, or 5'-position.PentosephosphatesGuanosine: 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)Dipyridamole: 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)Coformycin: A ribonucleoside antibiotic synergist and adenosine deaminase inhibitor isolated from Nocardia interforma and Streptomyces kaniharaensis. It is proposed as an antineoplastic synergist and immunosuppressant.N-Glycosyl Hydrolases: A class of enzymes involved in the hydrolysis of the N-glycosidic bond of nitrogen-linked sugars.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.DNA Glycosylases: A family of DNA repair enzymes that recognize damaged nucleotide bases and remove them by hydrolyzing the N-glycosidic bond that attaches them to the sugar backbone of the DNA molecule. The process called BASE EXCISION REPAIR can be completed by a DNA-(APURINIC OR APYRIMIDINIC SITE) LYASE which excises the remaining RIBOSE sugar from the DNA.ThymidineGuanine NucleotidesErythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.X Chromosome: The female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in human and other male-heterogametic species.Adenosine Deaminase Inhibitors: Drugs that inhibit ADENOSINE DEAMINASE activity.Adenylosuccinate Synthase: A carbon-nitrogen ligase. During purine ribonucleotide biosynthesis, this enzyme catalyzes the synthesis of adenylosuccinate from GTP; IMP; and aspartate with the formation of orthophosphate and GDP. EC 6.3.4.4.AminohydrolasesRibosemonophosphates: Ribose substituted in the 1-, 3-, or 5-position by a phosphoric acid moiety.DNA: 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).Pyrimidine Nucleotides: Pyrimidines with a RIBOSE and phosphate attached that can polymerize to form DNA and RNA.Tubercidin: 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.Dilazep: Coronary vasodilator with some antiarrhythmic activity.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Phosphoglycerate Kinase: An enzyme catalyzing the transfer of a phosphate group from 3-phospho-D-glycerate in the presence of ATP to yield 3-phospho-D-glyceroyl phosphate and ADP. EC 2.7.2.3.Adenosine Kinase: 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 2.7.1.20.Nucleotides: The monomeric units from which DNA or RNA polymers are constructed. They consist of a purine or pyrimidine base, a pentose sugar, and a phosphate group. (From King & Stansfield, A Dictionary of Genetics, 4th ed)Sex Chromosomes: The homologous chromosomes that are dissimilar in the heterogametic sex. There are the X CHROMOSOME, the Y CHROMOSOME, and the W, Z chromosomes (in animals in which the female is the heterogametic sex (the silkworm moth Bombyx mori, for example)). In such cases the W chromosome is the female-determining and the male is ZZ. (From King & Stansfield, A Dictionary of Genetics, 4th ed)Amidophosphoribosyltransferase: An enzyme, involved in the early steps of purine nucleotide biosynthesis, that catalyzes the formation of 5-phosphoribosylamine from glutamine and phosphoribosylpyrophosphate. EC 2.4.2.14.Gout: Hereditary metabolic disorder characterized by recurrent acute arthritis, hyperuricemia and deposition of sodium urate in and around the joints, sometimes with formation of uric acid calculi.