Uracil, incorporation

Nucleotide Uptake. When uracil labelled with tritium was supplied to 15-day-old ozone-treated cotton leaves, a 2-fold increase in uracil incorporation into the RNA fraction was observed (Table IV). In this one particular case, there appeared to be a greater percentage of uracil incorporation into RNA in treated tissue than in control tissue. 

Co-crystallisation of the 2,4-diamino-6-alkyltriazine 32 with uracil derivative 33 gave 1 1 co-crystals in which ADA-DAD pairs are linked into tapes through DA-AD interactions involving the uracils. Incorporation of hydroxymethyl groups into the 6-positions of the triazine and uracil tectons led to the tapes... 

Several analytes are known to be indicative of folate metabolism. Plasma total homocysteine increases when there is a deficiency of 5-MTHF, such that the methylation of homocysteine to methionine is compromised. However, though plasma homocysteine is considered to be a sensitive functional indicator, it is not specific because its concentration can be influenced by deficiency of other vitamins (Bg and B12) involved in the metabolism of homocysteine. Similarly the methylation of DNA is dependent upon adequate 5-MTHF. A sensitive new method for the rapid detection of abnormal methylation patterns in global DNA patterns has been reported and may have promise as a functional marker, as may the measurement of the degree of uracil incorporation into DNA, 5,10-metliylene THF being required for die conversion of deoxyuridine monophosphate (dUMP) to dTMP by thymidylate synthetase. ... 

Pourquier, P., Ueng, L. M., Kohlhagen, G., Mazumder, A., Gupta, M., Kohn, K. W., and Pommier, Y. (1997). Effects of uracil incorporation, DNA mismatches, and abasic sites on cleavage and religation activities of mammalian topoisomerase 1. J. Biol. Chem. 272, 7792-7796. 

Subsequent excision-repair of the DNA at the sites of uracil incorporation may only result in the re-incorporation of uracil in drug-treated cells because of the high dUTP dTTP ratio. This may lead to a futile cycle of uracil incorporation and excision resulting in an increase in the steady-state level of DNA strand breaks, a possible contributory factor leading ultimately to cell death. 

The existence of a phenotypic relaxation in aminoacid-starved cells has been shown with the inhibitor of chain elongation CHI. Addition, in vivo, of CHI increases total RNA in starved cells. However, the labelled uracile incorporated is not polymerized into r-RNAs molecules but in t-RNAs molecules, the only RNA whole synthesis is stimulated in this condition. ... 

A study of the mechanism of uracil incorporation into uridine phosphates was carried out in the Ehrlich ascites tumor, a tissue which utilized uracil as well as small molecule precimsors for nucleic acid formation (312). Uridine 5 -phosphate (UMP) was formed from uracil, ATP, and ribose 1-phosphate (R-l-P). Uridine was an intermediate in the formation of the nucleotide and was formed by the reaction of uracil and R-l-P with pyrimidine nucleoside phosphorylase (313, 314). Nucleoside kinase reacted the nucleoside with ATP to form UMP. The sequence is ... 

The sugars are typically ribose (ribonucleic acids, RNA), or 2-deoxyribose (deoxyribonucleic acids, DNA). There are five common bases in nucleic acids adenine (A) thymine (T) uracil (U) cytosine (C) and guanine (G). DNA polymers incorporate the four bases. A, T, C, and G, and RNA, the set A, U, C, and G. 

A required step for the in vivo incorporation of uracil into DNA is the... 

Fluorouracil (5-fluorouracil, 5-FU, Fig. 5) represents an early example of rational drag design in that it originated from the observation that tumor cells, especially from gut, incorporate radiolabeled uracil more efficiently into DNA than normal cells. 5-FU is a fluorinated pyrimidine analog that must be activated metabolically. In the cells 5-FU is converted to 5-fluoro-2>deoxyuridine-monophosphate (FdUMP). This metabolite inhibits thymidilate synthase which catalyses the conversion of uridylate (dUMP) to thymidilate (dTMP) whereby methylenetetrahydrofo-late plays the role of the carbon-donating cofactor. The reduced folate cofactor occupies an allosteric site of... 

An efficient preparation of 5-cyanouracils started from JV-ethoxycarbonylcyanoacetamide 47, the carbonyl of the urethane finally being incorporated into the uracil ring... 

DNA incorporates the monosaccharide deoxyribose, while RNA has ribose. One of the four bases is different RNA has uracil in place of thymine in DNA. Finally, RNA has no double helix. 

Most of the early methods for assigning isotopically labeled nucleic acids were developed using RNA samples, since 13C and 15N isotopes can be incorporated in RNA more easily than in DNA. While most of the magnetization transfer pathways in RNA and DNA are the same, the latter contains thymine rather than uracil. To remove the ambiguity of intra- and inter-residue H6-CH3 peak assignment in thymine, the HCCCH through-bond method was proposed [51] as a more sensitive alternative to NOE or ROE. 

A. Biotin Incorporate in base thymine in DNA probe sequence or uracil in RNA probe sequence... 

Although both orotic acid and uracil are utilized by Ehrlich ascites tumour cells in mice [52], the presence of orotic acid completely inhibits the incorporation of bicarbonate into C2 of the acid-soluble nucleotides in the same tumour system [181]. 

Although FdUrd produces only DNA-medicated cyotoxicity, 5-FU can also be metabolized to fluorouracil monophosphate (FUMP) and ultimately to fluorouracil triphosphate (FUTP), which can be incorporated into RNA in place of uridine triphosphate (UTP). In other words, incorporation of 5-FU into RNA mimics uracil de novo synthesis and affects the production of ribosomal RNAs (rRNAs) (16,17). 5 -FU also affects several aspects of messenger RNA (mRNA) function, including transcription (18), translation (19), and slicing (20). 

Table IV. Incorporation of Uracil - into the RNA fraction of 15-day-old 0 treated cotton cotyledon leaves...

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