Thymine chromatography

SOD ha T cell Tc TcR TGA Th TLC TMP/SMX TNF Ts TX U V domain VLA Ml H m superoxide dismutase half-life thymus-derived lymphocyte cytotoxic T cell T-cell receptor thymine-guanine-adenine T helper cell thin layer chromatography trimethoprim/sulphamethazole tumour necrosis factor T suppressor cell thromboxane unit variable domain very-late antigen microlitre (10 6 litre) micrometre (10"6 metre)... 

The formation of dimers other than thymine dimer in irradiated DNA has been recently reported by Setlow and Carrier,87 using E. coli DNA containing either labeled thymine (14C or tritium) or labeled cytosine (tritium). Three photoproducts could be isolated by chromatography of the acid hydrolysates of the irradiated DNA and were... 

High-performance liquid chromatography (HPLC) has been used to analyze metronidazole [1435-1437], misonidazole [1309,1438], and other nitroimidazoles [1435, 1439] in body fluids or pharmaceutical dosage forms. HPLC analysis of effect of hypoxic-cell radiosensitizer misonidazole on the radiation-induced reduction of DNA bases (thymine, cytosine, and adenine) has been carried out [1440, 1441], HPLC was employed to characterize different nitroimidazoles [327, 366, 388,409, 450, 1442-1444], nitropyrazoles [246, 301], nitrothiazoles [366], l-aryl(hetaryl)-4-nitro-l,2,3-triazoles [601], nitrobenzimidazoles [707], nitrobenzofurazans [774, 1445-1449], nitrobenzotriazoles [1450],... 

In the assay by Lu et al. (1992), the catabolites of uracil, thymine, or 5-fluorouracil were separated from the respective parent compounds by chromatography on two 5 /xm Hypersil columns (from Jones Chromatography, Littleton, CO) used in tandem. The mobile phase contained 1.5 mM potassium phosphate (pH 8.0 for 5-fluorouracil, pH 8.4 for thymine and uracil) and 5 mM tetrabutylammonium hydrogen sulfate. The column effluent was monitored at an appropriate wavelength in the UV region. 

The second method uses the conversion of [14C]-thymidine to [14C]-thymine or vice versa as separated by TFC. Unlike the spectrophotometric assay, data on linearity with time and protein concentration is available for the TFC assay (14). The main disadvantage of this particular method is the limitation of the number of samples that can be analyzed at one time owing to the capacity of the available chromatography equipment. 

Purines and pyrimidines are components of nucleic acids and are known to occur in soils. According to Bremner (1967), the nitrogen in purines and pyrimidines accounts for less than 1% of the total soil nitrogen. Much of the earlier information on the presence of these compounds comes from G. Anderson (1957, 1958, 1961) who identified guanine, adenine, cytosine, thymine, and traces of uracil in acid hydrolyzates of humic acids extracted from three Scottish soils. Anderson used paper and ion-exchange chromatography to detect and estimate the concentrations of nucleic acid bases. More... 

FIGURE 2. Ion-exclusion chromatography of (a) known purines and pyrimidines (b) purines and pyrimidines extracted from the B, . horizon of a Spodosol. HX = uracil U = unknown T = thymine G = guanine A = adenine C = cytosine MC = 5 methyl cytosine (Cortez and Schnitzer, 1979b). 

K.H. Cook, E.C. Friedberg (1976). Measurement of thymine dimers in DNA by thin-layer chromatography. Anal Biochem., 73,411-418. 

GC base pairs appear to be the preferred site of fixation of platinum(II) compounds on DNA. This conclusion is supported by three types of arguments. First, the rate of fixation of eis-DDP to DNA is correlated with its GC content (53). Hence, if ( is-DDP is mixed with two DNAs of different GC content, it will fix preferentially to the DNA with highest percentage of guanine (54, 55) Second, the quantity of purine bases which have not reacted with platinum can be determined by means of paper chromatography of the depurinated platinum-DNA complex. This experiment shows that d is-DDP reacts with guanine before it binds to adenine (56). Finally, raman spectroscopy of platinum-DNA complexes reveals that fresh aqueous solutions of c is-DDP react preferentially with guanine at r 0.2 and also with adenine at r = 0.4 whereas no reaction with cytosine or thymine was observed (37). 

A difficulty in finding inborn errors of pyrimidine metabolism by metabolite screening procedures is the absence of a typical end-product, like uric acid is in the purine metabolism. Moreover, pyrimidine metabolism is not easily accessible for simple chromatographic screening techniques. Nevertheless, with more complicated methods we are able to evaluate patterns of urinary pyrimidine bases and nucleosides. With routine gas-liquid chromatography (GLC) as is used for urinary organic acid analysis strongly increased uracil and thymine concentrations can be discovered. 

R = Tr) decomposed to thymine and the enone (611) in pyridine or during chromatography on silica gel. N.m.r. measurements have indicated that l-(6-deoxy-2,3-0-isopropylidene-a-L-/yxo-hexopyranosyl-4-ulose)thymine adopts a conformation, while 9-(6-deoxy-a-L-/yxo-hexopyranosyl-4-ulose)theo-... 

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