Structural and magnetic properties of purine and pyrimidine nucleotides (CMP, UMP, dTMP, AMP, GMP, IMP) were studied at different levels of ab initio molecular orbital theory. These calculations were performed at the hartree-fock level and density functional B3LYP methods. Geometries were fully optimized by following Cs symmetry restrictions. The standard 6-31G** basis set which includes polari...

structural and magnetic properties of purine and pyrimidine nucleotides (cmp, ump, dtmp, amp, gmp, imp) were studied at different levels of ab initio molecular orbital theory. these calculations were performed at the hartree-fock level and density functional b3lyp methods. geometries were fully optimized by following cs symmetry restrictions. the standard 6-31g** basis set which includes polari...

It has been suggested that carcinogenesis associated with chronic inflammation involves DNA damage by nitric oxide (NO) and other reactive species secreted from macrophages and neutrophils. The guanine moiety of DNA reacts with NO, yielding two major deamination products: xanthine (Xan) and oxanine (Oxa). Oxa reacts further with polyamines and DNA binding proteins to form cross-link adducts. In...

Thymidylate, a vital DNA precursor, is synthesized by thymidylate synthases (TSs). A second class of TSs, encoded by the thyX gene, is found in bacteria and a few other microbes and is especially widespread in anaerobes. TS encoded by thyX requires a flavin adenine dinucleotide prosthetic group for activity. In the oxidative half-reaction, the reduced flavin is oxidized by 2'-deoxyuridine 5'-mo...

The CDC8 gene of Saccharomyces cerevisiae encodes deoxythymidylate (dTMP) kinase and is required for nuclear and mitochondrial DNA replication in both the mitotic and meiotic cell cycles. All cdc8 temperature-sensitive mutants are partially defective in meiotic and mitochondrial functions at the permissive temperature. In a study of revertants of temperature-sensitive cdc8 mutants, the SOE201 a...

A quantitative comparison of the incorporation of methyl-sHthymidine and 6-sH-deoxyuridine into the DNA of Drosophila nzelanogaster in the presence and in the absence of 5-fluorouracil indicated that S-fluorouracil inhibits the reaction converting dUMP to dTMP catalysed by thymidylate synthetase (methylenetetrahydrofolate:dUrd-5’-P C-methyltransferase, E.C. 2.1.1 .b). The enzyme exhibits maxima...

The tritium atom of deoxyuridylate-5-3H is obligatorily displaced in the thymidylate synthetase reaction and equilibrates with water. Accordingly, a new and simple assay for the enzyme has been devised which is based on the measurement of the tritium released. This method shows essentially the same substrate requirements and pH optimum as the spectrophotometric assay. It has the advantage of mu...