Transcription of the carAB operon encoding the unique carbamoylphosphate synthase of Escherichia coli reflects the dual function of carbamoylphosphate in the biosynthesis of arginine and pyrimidine nucleotides. The tandem pair of promoters is regulated by various mechanisms depending on the needs of both pathways and the maintenance of a pyrimidine/purine nucleotide balance. Here we focus on th...

The title compound, C(15)H(13)ClN(6), contains two pyrimidine rings and one benzene ring, where the dihedral angle between the planes through the pyrimidine rings is 81.57 (10)°, and those between the pyrimidine rings and the benzene ring are 84.02 (8) and 89.46 (7)°, indicating that the three rings are almost perpendicular. In the crystal, inter-molecular N-H⋯N hydrogen bonds link the mol-ecul...

African trypanosomes are capable of both pyrimidine biosynthesis and salvage of preformed pyrimidines from the host. However, uptake of pyrimidines in bloodstream form trypanosomes has not been investigated, making it difficult to judge the relative importance of salvage and synthesis or to design a pyrimidine-based chemotherapy. Detailed characterization of pyrimidine transport activities in b...

In the title compound, C6H10N3(+)·Cl(-), the cation is essentially planar with an r.m.s. deviations of the fitted atoms of 0.008 Å. In the crystal, adjacent ions are linked by weak N-H⋯Cl hydrogen bonds involving the pyrimidine and amine N atoms, forming a three-dimensional network. C-H⋯π inter-actions between the methyl and pyrimidine groups and π-π stacking [centroid-centroid distance = 3.474...

Michael addition reaction of the 2-amino-1,3,4-thiadiazole to chalcone as biselectrophile afforded 5,7-diphenyl-6-[1,3-diphenylpropan-1-on-3-yl][1,3,4]thiadiazolo[3,2-a]pyrimidine (3) instead of 5,7-diphenyl-5H-[1,3,4]thiadiazolo[3,2-a]pyrimidine (5) via further Michael addition at C5 in pyrimidine moiety. The structure 3 was established through the aspect of ab initio calculations, elemental a...

cent sun lamp (280 to 400 nm), respectively. Enzymatic photoreactivation with yeast photoreactivating enzyme showed that -80% of the endonuclease-sensitive sites were cyclobutyl pyrimidine dimers. In both strains of mice the pyrimidine dimers remained in high-molecular-weight DNA for 24 hr after irradiation. These data show that mouse epi thelial cells in vivo have little or no capacity for the...

In the title compound, C15H18N2O3S, the hydro-pyrimidine ring adopts a sofa conformation with the methine C atom as the flap. The benzene ring is almost perpendicular to the mean plane of the hydro-pyrimidine ring, making a dihedral angle of 85.51 (8)°, and the meth-oxy O atom lies over the centre of the pyrimidine ring. In the crystal, weak N-H⋯S inter-actions form a zigzag chain running along...

In the title compound, C(24)H(25)N(3)S(2), the S-bound benzene rings have orthogonal [dihedral angle = 85.31 (9)°] and splayed [67.92 (11)°] orientations with respect to the pyrimidine ring; the dihedral angle between the benzene rings is 48.18 (12)°. The pentyl group has an extended all-trans conformation and lies to one side of the pyrimidine ring [the N(py)-C(py)-C(p)-C(p) torsion angle = -8...

C-5 alkynylated and N-1 alkylated pyrimidine derivatives were synthesized by N-alkylation reaction of 5-iodouracil in the presence of NaH, as a base, followed by Pd-catalyzed Sonogashira cross-coupling reaction of N-alkyl-5-iodouracil derivatives (1 and 2) with corresponding terminal alkynes. Intramolecular in situ O-heteroannulation ring closure of N-1-alkyl-C-5-alkynylpyrimidine derivatives (...

Loss of small, acid-soluble spore protein alpha reduced spore UV resistance 30- to 50-fold in Bacillus subtilis strains deficient in pyrimidine dimer repair, but gave only a 5- to 8-fold reduction in UV resistance in repair-proficient strains. However, both repair-proficient and -deficient spores lacking this protein had identical heat and gamma-radiation resistance.