Studies with Lactobadlus tichmannii have indicated that vitamin Blz is required for the reduction of formate to the methyl group of thymine (1). Such a function is in agreement with other data implicating the vitamin in methyl group neogenesis and in thymine synthesis (2, 3). The present experiments were designed to study the role of vitamin Bls in thymine biosynthesis by bone marrow. The resul...

Four double-headed nucleosides were prepared by the CuAAC reaction. Hereby, a triazole-containing linker connects an additional thymine or adenine to the 2'-position of 2'-deoxyuridine, a thymine to the 5'-position of thymidine and a thymine to the 6'-position of an LNA-thymidine monomer. Whereas no conclusive recognition effects of the additional thymines were found when introduced in LNA or a...

Thymidine phosphorylase (TP) catalyses the conversion of thymidine into thymine. A non-radiochemical assay procedure for TP was developed in which thymine was detected at 265 nm after separation with reversed-phase HPLC. A complete separation of thymidine and thymine was achieved in 6 min and the minimum amount of thymine that could be detected was 0.8 pmol. The assay was linear with reaction t...

To explore the excited-state structural dynamics of thymine, a DNA nucleobase, we measured the resonance Raman spectra of thymine in aqueous solution at wavelengths throughout the lowest-energy absorption band. Self-consistent analysis of the resulting resonance Raman excitation profiles and absorption spectrum using a time-dependent wave packet formalism yielded the excited-state structural dy...

When thymine auxotrophs are grown in the presence of methyl labelled [3H] or [14C] thymine which has been stored at 4 degrees C, two classes of material are labelled which are not DNA. One class sediments on neutral sucrose gradients with spontaneously single stranded Okazaki pieces, is unstable in alkali, migrates on alkaline gels as very small material and is digested by ribonucleases and mic...

We have studied the generation of reactive oxygen species during the metabolism of a carcinogen, benzo[a]pyrene, by human mammary epithelial cells. We have quantitated the production of one type of oxidative DNA damage, thymine glycols, by using a monoclonal antibody specific to this base modification. Thymine glycols were produced in DNA in a dose-dependent manner after exposure of human mamma...

In 1954, Cohen and Barner discovered that a thymine auxotrophic (thyA) mutant of Escherichia coli undergoes cell death in response to thymine starvation. This phenomenon, called thymineless death (TLD), has also been found in many other organisms, including prokaryotes and eukaryotes. Though TLD has been studied intensively, its molecular mechanism has not yet been explained. Previously we repo...

Stokes (1944) reported the replaceability of folic acid by thymine for Streptococcus lactis strain R as well as other folic-acid-requiring streptococci, and Fink et al. (1954) noted that high concentrations of recrystallized dihydrothymine supported growth of Streptococcus faecalis (ATCC 8043) deficient in both folic acid and thymine. The question arose, however, as to whether the latter respon...

The intraoellular concentration of thymidine triphosphate has been measured in thymine requiring mutants of Escherichia co&i K12 and E. coli 15, and compared with that in non-mutant strains using thymine, thymidine and a mixture of thymine and deoxyguenosine, in the growth medium. The data show (1) that the thymidine triphosphate concentration rises as the thymine concentration in the growth me...

5-Bromodeoxyuridine (BrUDr) is an effective inhibitor of the growth of E. coli and Lactobacitti, and this growth inhibition can be reversed by thymidine (1-3). There is evidence that this thymidine analog can replace the thymine of both E. coli and bacteriophage deoxyribonucleic acid (DNA) on an equimolar basis (7, 11, 12). In E. coli, nearly 50 per cent of the thymine can be replaced. Whereas ...