Evidence is summarized showing that thymine methyls are as important in the recognition of specific sequences by proteins as are the more widely recognized hydrogen bonding sites of bases in the major groove (1). Strongest evidence has come from experiments using functional group mutagenesis (2) in which thymines in a specific recognition sequence (e.g., promoters, operators and restriction sit...

The disposition and metabolic fate of 3'-deoxy-2',3'-didehydrothymidine (D4T) were evaluated both in isolated hepatocytes and in nonhuman primates. Rapid formation of thymine and beta-aminoisobutyric acid (BAIBA) occurred following incubation of hepatocytes with 10 microM [5(-3)H]D4T. Substantial levels of tritiated water were also detected. Exposure of cells to D4T in the presence of either 1 ...

The wobble hypothesis does not discriminate between uracil and thymine. Methylation could favor further stabilization of uracil in the keto form. Thymine is present in keto form only and can pair up but with adenine. Uracil can easily construct the enol form; that is why it forms the U-G pair. In previous E-print I proposed an alternative to the wobble hypothesis [1]. According to my reviewers ...

LTRAVIOLET irradiation produces dimers of thymine, thymine-cytosine and cytosine in deoxyribonucleic acid (DNA) (BEUKERS, IJLSTRA and BERENDS 1960; WACKER, DELLWEG and WEINBLUM 1960; SETLOW, CARRIER and BOLLUM 1965). UV light inactivates transforming DNA and induces thymine dimers in a parallel manner, as if the dimers block transforming activity (SETLOW and SETLOW 1962). Thymine dimers and thy...

Single-stranded DNA of coliphage M13mp8 was treated with the oxidizing agent, KMnO4, under conditions that selectively form cis-5,6-dihydro-5,6-dihydroxythymine (thymine glycol). Treatment of DNA with 0.7 and 1.4 mM KMnO4 introduced approximately 200 and 400 thymine glycol residues, respectively, per genome. When these DNAs were used to transform Escherichia coli, it was observed that phage sur...

1. The concentrations of RNA, DNA and protein are decreased in cells of Euglena gracilis var. bacillaris grown on suboptimum concentrations of vitamin B(12). 2. The addition of vitamin B(12) to deficient cells stimulates the incorporation of [(14)C]formate into the above cell components as well as into thymine of DNA and serine and methionine of protein. 3. In a cell-free system from vitamin B(...

One-electron oxidation of A/T-rich DNA leads to mutations at thymine. Experimental investigation of DNA containing methyl-deuterated thymine reveals a large isotope effect establishing that cleavage of this carbon-hydrogen bond is involved in the rate-determining step of the reaction. First-principles quantum calculations reveal that the radical cation (electron hole) generated by DNA oxidation...

Single-stranded DMA of coliphage M13mp8 was treated with the oxidizing agent, KMn04, under conditions that selectively form c/'s-5,6-dihydro-5,6-dihydroxythymine (thymine glycol). Treatment of DMA with 0.7 and 1.4 HIM KMnO< introduced approximately 200 and 400 thymine glycol residues, respectively, per genome. When these DMAs were used to transform Escherichia coli, it was observed that phage s...

R factor 1818 is shown to be eliminated from a thymineless strain of Escherichia coli J6-2 (R-1818) during thymine starvation. Readdition of thymine to the starved cultures produces a partial recovery in viable count but does not affect the proportion of R(-) cells. The R factor is not cured from exponential- or stationary-phase cultures which are starved of required amino acids as well as thym...