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Gan Sep 1955
Topics: Animals; Azaguanine; Guanine; Leadership; Neoplasms; Neoplasms, Experimental; Refractive Surgical Procedures
PubMed: 13262473
DOI: No ID Found -
Journal of Molecular Biology Dec 1965
Topics: Azaguanine; Bacillus cereus; Chemical Phenomena; Chemistry; Chemistry Techniques, Analytical; Hot Temperature; Hydroxyapatites; In Vitro Techniques; RNA, Bacterial; RNA, Transfer; Spectrophotometry
PubMed: 4956457
DOI: 10.1016/s0022-2836(65)80199-1 -
Proceedings of the National Academy of... Sep 1963
Topics: Azaguanine; Connective Tissue; Fibroblasts; Inosine Monophosphate; Metabolism; Pharmacology; Phosphotransferases; Research; Tissue Culture Techniques
PubMed: 14067106
DOI: 10.1073/pnas.50.3.568 -
Mutation Research 1982
Comparative Study
Topics: Animals; Azaguanine; Benzo(a)pyrene; Benzopyrenes; Benzyl Compounds; Biotransformation; Biphenyl Compounds; Cell Line; Cricetinae; Cricetulus; Drug Resistance; Lung; Male; Microsomes, Liver; Mutagenicity Tests; Mutagens; Mutation; Rats
PubMed: 6276737
DOI: 10.1016/0165-1218(82)90054-4 -
Acta - Unio Internationalis Contra... 1960
Topics: Animals; Antineoplastic Agents; Azaguanine; Mercaptopurine; Purines; Rats
PubMed: 13821915
DOI: No ID Found -
Genetika 1975Guanine, unlike adenine and hypoxanthine, can not eliminate the inhibitory effect of adenine analogues on the growth and flavinogenesis of Eremothecium ashbyii. Guanine...
Guanine, unlike adenine and hypoxanthine, can not eliminate the inhibitory effect of adenine analogues on the growth and flavinogenesis of Eremothecium ashbyii. Guanine does not restore riboflavin synthesis inhibited with 5-10(-3) M 8-azaguanine. Low adenine concentrations (10(-4)-3-10(-4) M), which do not influence the inhibitory effect of 5.-10(-3) M 8-azaguanine, restore the riboflavin synthesis in combination with guanine. On the basis of the data obtained as well as the data of biochemical analysis it is concluded that the riboflavin producer studied lacks guanosinemonophosphate reductase. The mutants resistant to various concentrations of 8-azaguanine have been obtained. In all mutants resistant to 8-azaguanine the efficiency of the incorporation of 14C-guanine and 14C-adenine into mycelium is decreased as compared with the susceptible strain. The mutant Azg-R 10 resistant to high (3-10(-3) M) concentrations of 8-azaguanine, 8-azaadenine and 2,6-diaminopurine secretes inosine-like compounds when grown in a synthetic medium. The stepwise increase of the mutant resistance to 8-azaguanine from 10(-4) M TO 3-10(-3) M did not result in further enhancement of riboflavin synthesis.
Topics: Ascomycota; Azaguanine; Mutagens; Riboflavin; Saccharomycetales
PubMed: 1240815
DOI: No ID Found -
Bioorganic Chemistry Oct 2003Watson-Crick optimized geometries and the energies of base pairing for the natural pairs of nucleic bases: adenine-thymine (AT) and guanine-cytosine (GC) have been...
Watson-Crick optimized geometries and the energies of base pairing for the natural pairs of nucleic bases: adenine-thymine (AT) and guanine-cytosine (GC) have been recalculated by ab initio methods in order to compare results to those found for the non-natural azaadenine-thymine (AAT) and azaguanine-cytosine (AGC) pairs. Geometry optimizations carried out at the HF/6-31G** level and energies obtained at MP2/6-31G**, show that AAT and AGC have hydrogen bonding patterns similar to the natural AT and GC and that the interaction energies (DeltaH0int) for the former are ca. 7 kcal/mol more stable than the latter. Accordingly, the pairs based on azapurines would be favored with respect to the natural pairs. Some possible explanations why nature does not use extensively the azabases in base pairing are given.
Topics: Azaguanine; Base Pairing; Cytosine; Hydrogen Bonding; Molecular Structure; Nucleic Acids; Thermodynamics; Thymine
PubMed: 12941289
DOI: 10.1016/s0045-2068(03)00083-x -
Mutation Research Sep 1976Low concentrations (less than or equal 20 mug/ml) of 8-azaguanine are 1000 fold more toxic to V79 Chinese hamster cells in medium containing 10% dialyzed fetal calf...
Low concentrations (less than or equal 20 mug/ml) of 8-azaguanine are 1000 fold more toxic to V79 Chinese hamster cells in medium containing 10% dialyzed fetal calf serum than in medium containing 10% undialyzed serum. Serum enzyme activity that converts AG to nontoxic 8-azaxanthine degrades AG at the same rate, whether or not the serum is dialyzed. However, cytotoxicity results similar to those obtained with US were produced in medium containing DS and 2.5 mug of hypoxanthine (HX)/ml (DSH). Therefore, serum HX is considered to be responsible for the relatively low cytotoxicity of AG in medium containing US. Colonies that arose in medium containing AG were isolated and characterized. Those that remained resistant to AG (40 mug/ml) and sensitive to aminopterin in the presence of HX and thymidine (HAT) were considered mutants; non-mutants were sensitive to AG and resistant to HAT. Colonies isolated from medium containing DSH or US and low concentrations of AG were not mutants, but those from medium containing high concentrations (greater than or equal 30 mug/ml) of AG were mutants. Spontaneous and N-methyl-N-nitro-N-nitrosoguanidine induced mutants were detectable in medium containing DSH without replating the cells prior to adding AG (greater than or equal 30 mug/ml), but in order to detect MNNG induced mutations in medium containing DS replating was essential. In DS, the mutation frequency increased as an exponential function of the toxicity of MNNG, but remained two orders of magnitude lower than the induced mutation frequencies that occurred in DSH. HX, in DSH or US, produced profound effects, other than interference with AG toxicity, that distort the results of mutagenesis assays. To study mutation using AG resistance as the endpoint, it is essential to use dialyzed serum.
Topics: Azaguanine; Blood; Cell Line; Cell Survival; Culture Media; Drug Resistance; Enzymes; Methylnitronitrosoguanidine; Mutagens; Mutation; Time Factors
PubMed: 958230
DOI: 10.1016/0027-5107(76)90244-x -
Mutagenesis Mar 199115-Oxosteviol, postulated to be the mutagenic metabolite of steviol, was observed to be non-mutagenic in preliminary experiments using a number of different systems....
Interpretation of results with the 8-azaguanine resistance system in Salmonella typhimurium: no evidence for direct acting mutagenesis by 15-oxosteviol, a possible metabolite of steviol.
15-Oxosteviol, postulated to be the mutagenic metabolite of steviol, was observed to be non-mutagenic in preliminary experiments using a number of different systems. Repetition of the original experiment in Salmonella TM677 failed to show any significant induction of 8-azaguanine resistant mutants by 15-oxosteviol even when the number of bacteria tested was greatly increased. Examination of the earlier positive result showed that it could not be justified from the data and revealed a commonly applied way of mishandling data obtained with the TM677 system.
Topics: Azaguanine; Dimethyl Sulfoxide; Diterpenes; Diterpenes, Kaurane; Drug Resistance, Microbial; Mutagenicity Tests; Mutation; Salmonella typhimurium
PubMed: 2056919
DOI: 10.1093/mutage/6.2.165 -
Advances in Morphogenesis 1973
Review
Topics: Azaguanine; Cell Differentiation; Cell Division; Cell Nucleus; Contact Inhibition; Culture Media; DNA; Karyometry; Morphogenesis; Nucleic Acids; Photic Stimulation; Photosynthesis; Plant Development; Plant Proteins; Plants; RNA; Spores; Time Factors
PubMed: 4581328
DOI: 10.1016/b978-0-12-028610-2.50009-5