نتایج جستجو برای: pyrimidine
تعداد نتایج: 9900 فیلتر نتایج به سال:
We compared the removal of pyrimidine(6-4)pyrimidone photoproducts [(6-4) photoproducts] and cyclobutane pyrimidine dimers (CPDs) from the genome of repair-proficient Escherichia coli, using monoclonal antibodies specific for each type of lesion. We found that (6-4) photoproducts were removed at a higher rate than CPDs in the first 30 min following a moderate UV dose (40 J/m2). The difference i...
4,6-Dichloro-2-(methylthio)pyrimidine (3) reacts with EtONa in EtOH, at ca. 20 ◦C, for 2 h, to give exclusively 4-chloro-6-ethoxy-2-(methylthio)pyrimidine (5) in 89% yield. The latter is presented as a useful multifunctionalised pyrimidine scaffold.
The formation of pyridine-pyrimidine- and pyrimidine-pyrimidine base pairs after in vitro DNA replication with the large fragment of Escherichia coli DNA polymerase I indicates that Watson-Crick-like base pairing between pyrimidine bases can occur in the enzyme due to the presence of the rare tautomers of deoxycytidylate and thymidylate in the template strand. The implications to mispair format...
Analogs of alternating purine-pyrimidine DNA polymers such as poly(dA-dT)-poly(dA-dT) can be made with phosphorothioate groups in the DNA backbone. A phosphorothioate diester at the 5'-purine-pyrimidine-3' step causes a significant lowering of the polymer's melting temperature compared to a phosphorothioate diester at the 5'-pyrimidine-purine-3' step. This may occur because sulfur substitution ...
Fused pyrimidine cores are privileged kinase scaffolds, yet few examples of the 2-amino-pyrido[3,4-d]pyrimidine chemotype have been disclosed in the context of kinase inhibitor programs. Furthermore, no general synthetic route has been reported to access 2-amino-pyrido[3,4-d]pyrimidine derivatives. Here we report a versatile and efficient chemical approach to this class of molecules. Our strate...
Spectroscopic and computational insight into weak noncovalent interactions in crystalline pyrimidine
Effects of weak C-H· · ·N interactions on the vibrational spectrum of crystalline pyrimidine are studied using Raman spectroscopy and electronic structure computations. When pyrimidine transitions from the liquid to solid state, peaks in the Raman spectrum exhibit non-uniform shifts. Calculations performed on a cluster of nine pyrimidine molecules (one pyrimidine molecule embedded in a field of...
We describe the clinical. hematologic. and biochemical findings in eight patients with pyrimidine-5’-nucleotidase deficiency occurring in six unrelated families. In most cases, a profound lowering of red cell pyrimidine-5’-nucleotidase activity. associated with the characteristic change in the u.v. spectrum brought about by increased levels of pyrimidine nucleotides was observed. One patient ha...
Considerable interest has been focused on the triazole structure, which has been known to possess a broad spectrum of biological activities such as antitumor, anti-inflammatory, antimicrobial, antiviral, and anticonvulsant activities. Before this, several heterocyclic compounds containing triazole were synthesized that had shown considerable anticonvulsant activity. As part of our continuous re...
Glutamine (Gln) prevents apoptosis in intestinal epithelial cells, but the mechanism(s) remain unknown. Gln-derived metabolites include ammonia, glutamate (Glu), glutathione (GSH), and nucleotides. We previously showed that Gln potently inhibited apoptosis in cytokine-treated human colonic HT-29 cells; this effect was specific to Gln, unaffected by Glu, and unrelated to intracellular GSH. The c...
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