A DNA repair enzyme that is an N-glycosyl hydrolase with specificity for DNA-containing ring-opened N(7)-methylguanine residues.
A class of enzymes involved in the hydrolysis of the N-glycosidic bond of nitrogen-linked sugars.
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.
An enzyme which catalyzes an endonucleolytic cleavage near PYRIMIDINE DIMERS to produce a 5'-phosphate product. The enzyme acts on the damaged DNA strand, from the 5' side of the damaged site.
A group of amides with the general formula of R-CONH2.
Guanine is a purine nucleobase, one of the four nucleobases in the nucleic acid of DNA and RNA, involved in forming hydrogen bonds between complementary base pairs in double-stranded DNA molecules.
An enzyme that catalyzes the HYDROLYSIS of the N-glycosidic bond between sugar phosphate backbone and URACIL residue during DNA synthesis.
An enzyme that removes THYMINE and URACIL bases mispaired with GUANINE through hydrolysis of their N-glycosidic bond. These mispaired nucleotides generally occur through the hydrolytic DEAMINATION of 5-METHYLCYTOSINE to thymine.
Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.
The reconstruction of a continuous two-stranded DNA molecule without mismatch from a molecule which contained damaged regions. The major repair mechanisms are excision repair, in which defective regions in one strand are excised and resynthesized using the complementary base pairing information in the intact strand; photoreactivation repair, in which the lethal and mutagenic effects of ultraviolet light are eliminated; and post-replication repair, in which the primary lesions are not repaired, but the gaps in one daughter duplex are filled in by incorporation of portions of the other (undamaged) daughter duplex. Excision repair and post-replication repair are sometimes referred to as "dark repair" because they do not require light.
A nucleoside consisting of the base guanine and the sugar deoxyribose.
A family of 6-membered heterocyclic compounds occurring in nature in a wide variety of forms. They include several nucleic acid constituents (CYTOSINE; THYMINE; and URACIL) and form the basic structure of the barbiturates.
A genotoxicological technique for measuring DNA damage in an individual cell using single-cell gel electrophoresis. Cell DNA fragments assume a "comet with tail" formation on electrophoresis and are detected with an image analysis system. Alkaline assay conditions facilitate sensitive detection of single-strand damage.
Compounds with a 5-membered ring of four carbons and an oxygen. They are aromatic heterocycles. The reduced form is tetrahydrofuran.
A group of enzymes catalyzing the endonucleolytic cleavage of DNA. They include members of EC 3.1.21.-, EC 3.1.22.-, EC 3.1.23.- (DNA RESTRICTION ENZYMES), EC 3.1.24.- (DNA RESTRICTION ENZYMES), and EC 3.1.25.-.
A potent hepatotoxic and hepatocarcinogenic mycotoxin produced by the Aspergillus flavus group of fungi. It is also mutagenic, teratogenic, and causes immunosuppression in animals. It is found as a contaminant in peanuts, cottonseed meal, corn, and other grains. The mycotoxin requires epoxidation to aflatoxin B1 2,3-oxide for activation. Microsomal monooxygenases biotransform the toxin to the less toxic metabolites aflatoxin M1 and Q1.
Proteins obtained from ESCHERICHIA COLI.
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).
Penetrating, high-energy electromagnetic radiation emitted from atomic nuclei during NUCLEAR DECAY. The range of wavelengths of emitted radiation is between 0.1 - 100 pm which overlaps the shorter, more energetic hard X-RAYS wavelengths. The distinction between gamma rays and X-rays is based on their radiation source.
The products of chemical reactions that result in the addition of extraneous chemical groups to DNA.
A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.
Uracil is a nitrogenous base, specifically a pyrimidine derivative, which constitutes one of the four nucleobases in the nucleic acid of RNA (ribonucleic acid), pairing with adenine via hydrogen bonds during base-pairing. (25 words)
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.
5-Hydroxymethyl-6-methyl- 2,4-(1H,3H)-pyrimidinedione. Uracil derivative used in combination with toxic antibiotics to lessen their toxicity; also to stimulate leukopoiesis and immunity. Synonyms: pentoksil; hydroxymethylmethyluracil.
A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.
A disturbance in the prooxidant-antioxidant balance in favor of the former, leading to potential damage. Indicators of oxidative stress include damaged DNA bases, protein oxidation products, and lipid peroxidation products (Sies, Oxidative Stress, 1991, pxv-xvi).
A DNA repair enzyme that catalyses the excision of ribose residues at apurinic and apyrimidinic DNA sites that can result from the action of DNA GLYCOSYLASES. The enzyme catalyzes a beta-elimination reaction in which the C-O-P bond 3' to the apurinic or apyrimidinic site in DNA is broken, leaving a 3'-terminal unsaturated sugar and a product with a terminal 5'-phosphate. This enzyme was previously listed under EC 3.1.25.2.
An enzyme which catalyzes the endonucleolytic cleavage of phosphodiester bonds at purinic or apyrimidinic sites (AP-sites) to produce 5'-Phosphooligonucleotide end products. The enzyme prefers single-stranded DNA (ssDNA) and was formerly classified as EC 3.1.4.30.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).
The rate dynamics in chemical or physical systems.
Enzymes that catalyze the cleavage of a carbon-oxygen bond by means other than hydrolysis or oxidation. EC 4.2.
Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.
The presence of an uncomplimentary base in double-stranded DNA caused by spontaneous deamination of cytosine or adenine, mismatching during homologous recombination, or errors in DNA replication. Multiple, sequential base pair mismatches lead to formation of heteroduplex DNA; (NUCLEIC ACID HETERODUPLEXES).
A pyrimidine base that is a fundamental unit of nucleic acids.
Uracil nucleotides which contain deoxyribose as the sugar moiety.
Thymine is a pyrimidine nucleobase, one of the four nucleobases in the nucleic acid of DNA (the other three being adenine, guanine, and cytosine), where it forms a base pair with adenine.
Hydrolysate of DNA in which purine bases have been removed.
A purine base and a fundamental unit of ADENINE NUCLEOTIDES.
The removal of an amino group (NH2) from a chemical compound.
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 purine and a reaction intermediate in the metabolism of adenosine and in the formation of nucleic acids by the salvage pathway.
Compounds based on imidazolidine dione. Some derivatives are ANTICONVULSANTS.
A methylated nucleotide base found in eukaryotic DNA. In ANIMALS, the DNA METHYLATION of CYTOSINE to form 5-methylcytosine is found primarily in the palindromic sequence CpG. In PLANTS, the methylated sequence is CpNpGp, where N can be any base.
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)
The covalent bonding of an alkyl group to an organic compound. It can occur by a simple addition reaction or by substitution of another functional group.
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)
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Highly reactive chemicals that introduce alkyl radicals into biologically active molecules and thereby prevent their proper functioning. Many are used as antineoplastic agents, but most are very toxic, with carcinogenic, mutagenic, teratogenic, and immunosuppressant actions. They have also been used as components in poison gases.
An alkylating agent in cancer therapy that may also act as a mutagen by interfering with and causing damage to DNA.
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.
Interruptions in one of the strands of the sugar-phosphate backbone of double-stranded DNA.
A family of THERMOPROTEALES consisting of variable length rigid rods without septa. They grow either chemolithoautotrophically or by sulfur respiration. The four genera are: PYROBACULUM; THERMOPROTEUS; Caldivirga; and Thermocladium. (From Bergey's Manual of Systematic Bacteriology, 2d ed)
Pairing of purine and pyrimidine bases by HYDROGEN BONDING in double-stranded DNA or RNA.
A class of inorganic or organic compounds that contain the borohydride (BH4-) anion.
The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.
Dimers found in DNA chains damaged by ULTRAVIOLET RAYS. They consist of two adjacent PYRIMIDINE NUCLEOTIDES, usually THYMINE nucleotides, in which the pyrimidine residues are covalently joined by a cyclobutane ring. These dimers block DNA REPLICATION.
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.
The region of an enzyme that interacts with its substrate to cause the enzymatic reaction.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.
A DNA repair enzyme that catalyzes DNA synthesis during base excision DNA repair. EC 2.7.7.7.
Double-stranded nucleic acid molecules (DNA-DNA or DNA-RNA) which contain regions of nucleotide mismatches (non-complementary). In vivo, these heteroduplexes can result from mutation or genetic recombination; in vitro, they are formed by nucleic acid hybridization. Electron microscopic analysis of the resulting heteroduplexes facilitates the mapping of regions of base sequence homology of nucleic acids.
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
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.
Viruses whose host is Bacillus. Frequently encountered Bacillus phages include bacteriophage phi 29 and bacteriophage phi 105.
The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.
Process of generating a genetic MUTATION. It may occur spontaneously or be induced by MUTAGENS.
A genus of rod-shaped, almost rectangular ARCHAEA, in the family THERMOPROTEACEAE. Organisms are facultatively aerobic or strictly anaerobic, grow on various organic substrates, and are found in continental solfataras.