PyrazolopyrimidinePyrimidonePolyoxins: Polyoxins are a group of nucleoside antibiotics composed of heterocyclic moieties containing nitrogen. An example is Polyoxin B.Orotic acidOrotate phosphoribosyltransferaseUVB-induced apoptosis: UVB-induced apoptosis is the programmed cell death of cells that become damaged by ultraviolet rays. This is notable in skin cells, to prevent melanoma.Uracil in DNA: DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms.PurinePyrC leader: In molecular biology, the PyrC leader is a cis-regulatory RNA element found at the 5' of the PyrC mRNA in Enterobacteria. The PyrC gene encodes Dihydroorotase, an enzyme involved in pyrimidine biosynthesis.Aspartate carbamoyltransferase: Aspartate carbamoyltransferase (also known as aspartate transcarbamoylase or ATCase) catalyzes the first step in the pyrimidine biosynthetic pathway ().Purine nucleotide cycle: The Purine Nucleotide Cycle is a metabolic pathway in which fumarate is generated from aspartate in order to increase the concentration of Krebs cycle intermediates.Salway, J.Orotidine 5'-phosphate decarboxylaseCytidineDihydroorotate dehydrogenase (quinone): Dihydroorotate dehydrogenase (quinone) (, dihydroorotate:ubiquinone oxidoreductase, (S)-dihydroorotate:(acceptor) oxidoreductase, (S)-dihydroorotate:acceptor oxidoreductase, DHOdehase (ambiguous), DHOD (ambiguous), DHODase (ambiguous), DHODH) is an enzyme with system name (S)-dihydroorotate:quinone oxidoreductase. This enzyme catalyses the following chemical reactionPyrimidine metabolism: Pyrimidine biosynthesis occurs both in the body and through organic synthesis.Arabinosyltransferase: In molecular biology, an arabinosyltransferase is a transferase enzyme acting upon arabinose."Reconstitution of functional mycobacterial arabinosyltransferase AftC proteoliposome and assessment of decaprenylphosphorylarabinose analogues as arabinofuranosyl donors.ThymineNucleoside analogue: Nucleoside analogues are nucleosides which contain a nucleic acid analogue and a sugar. Nucleotide analogs are nucleotides which contain a nucleic acid analogue, a sugar and one to three phosphate groups.Cis-acting replication element: Cis-acting replication elements brings together the 5' and 3' ends during replication of positive sense single stranded RNA viruses (for example Picornavirus, Flavivirus, coronavirus, togaviruses, Hepatitis C virus) and double stranded RNA viruses (for example rotavirus and reovirus).Base excision repair: frame|right|Basic steps of base excision repair|Basic steps of base excision repairLodenosineUridine triphosphateDepurination: Depurination is a chemical reaction of purine deoxyribonucleosides, deoxyadenosine and deoxyguanosine, and ribonucleosides, adenosine or guanosine, in which the β-N-glycosidic bond is hydrolytically cleaved releasing a nucleic base, adenine or guanine, respectively. The second product of depurination of deoxyribonucleosides and ribonucleosides is sugar, 2’-deoxyribose and ribose, respectively.DNA condensation: DNA condensation refers to the process of compacting DNA molecules in vitro or in vivo. Mechanistic details of DNA packing are essential for its functioning in the process of gene regulation in living systems.DeoxyuridineSymmetry element: A symmetry element is a point of reference about which symmetry operations can take place. In particular, symmetry elements can be centers of inversion, axes of rotation and mirror planes.MizoribineNTP binding site: An NTP binding site is a type of binding site found in nucleoside monophosphate (NMP) kinases, N can be adenosine or guanosine. A P-loop is one of the structural motifs common for nucleoside triphosphate (NTP) binding sites, it interacts with the bound nucleotide's phosphoryl groups.Thiamine transporter: Members of this protein family have been assigned as thiamine transporters by a phylogenomic analysis of families of genes regulated by the THI element, a broadly conserved RNA secondary structure element through which thiamine pyrophosphate (TPP) levels can regulate transcription of many genes related to thiamine transport, salvage, and de novo biosynthesis. Species with this protein always lack the ThiBPQ ABC transporter.Carbamoyl phosphateNucleic acid structure: Nucleic acid structure refers to the structure of nucleic acids such as DNA and RNA. Chemically speaking, DNA and RNA are very similar.List of strains of Escherichia coli: Escherichia coli is a well studied bacterium that was first identified by Theodor Escherich, after whom it was later named.Coles PhillipsG2-M DNA damage checkpoint: The G2-M DNA damage checkpoint is an important cell cycle checkpoint in eukaryotic organisms ranging from yeast to mammals. This checkpoint ensures that cells don't initiate mitosis before they have a chance to repair damaged DNA after replication.Burst kinetics: Burst kinetics is a form of enzyme kinetics that refers to an initial high velocity of enzymatic turnover when adding enzyme to substrate. This initial period of high velocity product formation is referred to as the "Burst Phase".DNA demethylation: DNA demethylation is the process of removal of a methyl group from nucleotides in DNA. DNA demethylation could be passive or active.Excinuclease: Excision endonuclease, also known as excinuclease or UV-Specific Endonuclease, is a nuclease (enzyme) which excises a fragment of nucleotides during DNA repair. The excinuclease cuts out a fragment by hydrolyzing two phosphodiester bonds, one on either side of the lesion in the DNA.Thymidine diphosphateFluorouracilTRNA (adenine57-N1/adenine58-N1)-methyltransferase: TRNA (adenine57-N1/adenine58-N1)-methyltransferase (, TrmI, PabTrmI, AqTrmI, MtTrmI) is an enzyme with system name S-adenosyl-L-methionine:tRNA (adenine57/adenine58-N1)-methyltransferase. This enzyme catalyses the following chemical reactionSurE, survival protein E: In molecular biology, the protein domain surE refers to survival protein E. It was originally found that cells that did not contain this protein, could not survive in the stationary phase, at above normal temperatures, and in high-salt media.Abscription: During normal transcription, RNA polymerase transcribes a number of short nonproductive oligonucleotides, and this process is called abortive transcription. The trapped RNAPs have been named abscriptases and the synthesis of specific length oligonucleotides called abscription.Silent mutation: Silent mutations are mutations in DNA that do not significantly alter the phenotype of the organism in which they occur. Silent mutations can occur in non-coding regions (outside of genes or within introns), or they may occur within exons.RNTP: A ribonucleoside tri-phosphate (rNTP) is a ribonucleoside with 3 phosphate groups. rNTPs are the building blocks of RNA synthesis as well as the synthesis of primers in DNA replication.Deoxycytidine monophosphateXeroderma pigmentosumSpecificity constant: In the field of biochemistry, the specificity constant (also called kinetic efficiency or k_{cat}/K_{M}), is a measure of how efficiently an enzyme converts substrates into products. A comparison of specificity constants can also be used as a measure of the preference of an enzyme for different substrates (i.Ethyl groupDihydrofolate reductase inhibitor: A dihydrofolate reductase inhibitor (DHFR inhibitor) is a molecule that inhibits the function of dihydrofolate reductase, and is a type of antifolate.CpG OligodeoxynucleotideDeoxyuridine monophosphateArchaeosine synthase: Archaeosine synthase (, ArcS, TgtA2, MJ1022 (gene), glutamine:preQ0-tRNA amidinotransferase) is an enzyme with system name L-glutamine:7-cyano-7-carbaguanine aminotransferase. This enzyme catalyses the following chemical reactionOxoguanine glycosylase: 8-Oxoguanine glycosylase also known as OGG1 is a DNA glycosylase enzyme that, in humans, is encoded by the OGG1 gene. It is involved in base excision repair.Thymidine triphosphatePhosphotransferase: Phosphotransferases are a category of enzymes (EC number 2.7) that catalyze phosphorylation reactions.BromacilConcentrative nucleoside transporter: Human concentrative nucleoside transporters include SLC28A1, SLC28A2 and SLC28A3 proteins. SLC28A2 is a purine-specific Na+-nucleoside cotransporter localised to the bile canalicular membrane.Carbamoyl phosphate synthetaseIsoxazoleThymidine monophosphateReaction coordinateExcision repair cross-complementing: Excision repair cross-complementing (ERCC) is a set of proteins which are involved in DNA repair.Biginelli reaction: The Biginelli reaction is a multiple-component chemical reaction that creates 3,4-dihydropyrimidin-2(1H)-ones 4 from ethyl acetoacetate 1, an aryl aldehyde (such as benzaldehyde 2), and urea 3. It is named for the Italian chemist Pietro Biginelli.Thymidylate synthase inhibitor: Thymidylate synthase inhibitors are chemical agents which inhibit the enzyme thymidylate synthase and have potential as an anticancer chemotherapy. Five agents were in clinical trials in 2002: raltitrexed, pemetrexed, nolatrexed, ZD9331, and GS7904L.Thymidylate kinaseBase pair: Base pairs (unit: bp), which form between specific nucleobases (also termed nitrogenous bases), are the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA. Dictated by specific hydrogen bonding patterns, Watson-Crick base pairs (guanine-cytosine and adenine-thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence.Spin–lattice relaxation in the rotating frame: Spin–lattice relaxation in the rotating frame is the mechanism by which Mxy, the transverse component of the magnetization vector, exponentially decays towards its equilibrium value of zero, under the influence of a radio frequency (RF) field in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). It is characterized by the spin–lattice relaxation time constant in the rotating frame, T1ρ.Crosslinking of DNA: In genetics, crosslinking of DNA occurs when various exogenous or endogenous agents react with two different positions in the DNA. This can either occur in the same strand (intrastrand crosslink) or in the opposite strands of the DNA (interstrand crosslink).DNA binding site: DNA binding sites are a type of binding site found in DNA where other molecules may bind. DNA binding sites are distinct from other binding sites in that (1) they are part of a DNA sequence (e.