Nucleic acids methylation

Nucleic acids Methyl green-pyronine Ethidium bromide RNA—red DNA—blue Fluoresces under UV when bound to DNA... 

Christman, J. K. et al., Reversibility of changes in nucleic acid methylation and gene expression induced in rat liver by severe dietary methyl deficiency, Carcinogenesis, 14, 551-557, 1993. 

The effects of pregnenolone-Iba-carbonitrile and phenobarbitone, which are protective against DMN toxicity and/or carcinogenicity, on DMN metabolism in liver slices were also investigated 28, 278, 438). Pretreatment of rats with pregnenolone-16a-carbonitrile resulted in a 20% decrease in C02 production from [ C]DMN but no change in nucleic acid methylation a decrease in C02 production was also observed after phenobarbitone pretreatment. These results are in agreement with the effects of these substances on hepatic DMN demethylase I activity 10, 11). 

Study of the biological significance of methylation has barely started. In fact, it has been known for a long time that a small number of DNA and RNA bases were methylated, but since the role of methylation was not obvious and only a small number of the bases were methylated, it was concluded that methylation played only a secondary biological role. It was even proposed that these reactions were only remnants of some more primitive type of function, or that nucleic acid methylation was an unspecific event serving to absorb excess methyl groups. But if every cell contains at least 14 different methylases, it is unlikely that nucleic acid methylation is purposeless. 

Nucleic Acids Methyl green-pyronlne DNA-blue, RNA-red sensitive... 

Among post-transcriptional modifications of nucleic acids, methylation is the most frequent one a number of methylated nucleosides have been isolated from all types of nucleic acids. ... 

Table 28 2 doesn t include all of the nucleoside components of nucleic acids The presence of methyl groups on pyrimidine and purine rings is a common and often important variation on the general theme... 

Woodward s synthesis, 4, 416-419 Chlorophyll b, 4, 382 Chlorophyll c, 4, 382 Chlorophyll d, 4, 382 Chlorophylls, 4, 378 biosynthesis reviews, 1, 99 structure, 4, 370 substituents reactions, 4, 402 Chloroporphyrin e, 4, 404 Chloroprothixene pharmacology, 3, 942 Chloropyramine as antihistamine, 1, 177 Chloropyrifos synthesis, 2, 201 Chloropyrifos-ethyl as insecticide, 2, 516 Chloropyrifos-methyl as insecticide, 2, 516 Chloroquine, 1, 145 adsorption on nucleic acids, 1, 179 as antimalarial, 1, 173, 2, 517 Chloroquine, hydroxy-as antimalarial, 2, 517 Chlorosulfonyl isocyanate cycloaddition reactions... 

Dacarbazine is activated by photodecomposition (chemical breakdown caused by radiant energy) and by enzymatic N-demethylation. Formation of a methyl carbonium ion results in methylation of DNA and RNA and inhibition of nucleic acid and protein synthesis. Cells in all phases of the cell cycle are susceptible to dacarbazine. The drug is not appreciably protein bound, and it does not enter the central nervous system. 

Stein D, Foster E, Huang SB, Weller D, Summerton J (1997) A spedfidty comparison of four antisense types morphoUno, 2 -0-methyl RNA, DNA, and phosphorothioate DNA, Antisense Nucleic Acid Drug Dev 7 151-157... 

Boulm F., Freund F., Moreau S., Nielsen P.E., Gryaznov S., Toulme J.J., Litvak S. Modified (PNA, 2-O-methyl and phosphoramidate) anti-TAR anti-sense oligonucleotides as strong and specific inhibitors of in vitro HI.V.-l reverse transcription. Nucleic Acids Res. 1998 26 5492-5500. 

Kim, Y Morris, MD, Pulsed Field Capillary Electrophoresis of Multikilobase Length Nucleic Acids in Dilute Methyl Cellulose Solutions, Analytical Chemistry 66, 3081, 1994. 

Small quantities of additional purines and pyrimidines occur in DNA and RNAs. Examples include 5-methyl-cytosine of bacterial and human DNA, 5-hydroxy-methylcytosine of bacterial and viral nucleic acids, and mono- and di-N-methylated adenine and guanine of... 

Nucleic acids contain, in addition to A, G, C, T, and U, traces of 5-methylcytosine, 5-hydroxymethylcyto-sine, pseudouridine ( P), or N-methylated bases. 

Much research has centered on identifying the source of the purine ring in caffeine. Two possible sources are likely methylated nucleotides in the nucleotide pool and methylated nucleotides in nucleic acids. Extensive experimental work by Suzuki and Takahashi27-30 proposes a scheme whereby caffeine is synthesized from methylated purines in the nucleotide pool via 7-methylxanthosine and theobromine. Information relating to the formation of 7-methylxanthine from nucleotides in the nucleotide pool is sparse. They also provide data that demonstrate that theophylline is synthesized from 1-methyladenylic acid through 1-methylxanthine as postulated by Ogutuga and Northcote.31... 

Bakalarski, G., P. Grochowski, J. S. Kwiatkowski, B. Lesyng, and J. Leszczynski. 1996. Molecular and electrostatic properties of the N-methylated nucleic acid bases by density functional theory. Chem. Phys. 204, 301. 

Cieplak, P., Caldwell, J. W., Kollman, P. A., Molecular mechanical models for organic and biological systems going beyond the atom centered two body additive approximation aqueous solution free energies of methanol and IV-methyl acetamide, nucleic acid base, and amide hydrogen bonding and chloroform/water partition coefficients of the nucleic acid bases, J. Comput. Chem. 2001, 22, 1048-1057... 

Fabani MM, Gait MJ (2008) miR-122 targeting with LNA/2 -0-methyl oligonucleotide mixmers, peptide nucleic acids (PNA), and PNA-peptide conjugates. RNA 14 336-346... 

N-AryInitrones (XIII) formed by oxidation of N-hydroxy-N-methyl arylamines, show high reactivity toward carbon-carbon and carbon-nitrogen double bonds in non-aqueous media (21,203) (Figure 10). Under physiological conditions, however, it appears that N-arylnitrones exist as protonated salts that readily hydrolyze to formaldehyde and a primary N-hydroxy arylamine and efforts to detect N-arylnitrone addition products in cellular lipid, protein or nucleic acids have not been successful (204). Nitroxide radicals derived from N-hydroxy-MAB have also been suggested as reactive intermediates (150), but their direct covalent reaction with nucleic acids has been excluded (21). 

Biomolecular MS and in particular MALDI-TOF-MS (see Sections 2.1.22 and 2.2.1) permit the routine analysis of oligonucleotides up to 70-mers, intact nucleic acids, and the direct detection of DNA products with no primer labels with an increase in analysis speed and mass accuracy especially in contrast to traditional DNA separation techniques such as slab gels or capillary electrophoresis. Applications focus on the characterization of single nucleotide polymorphisms (SNPs) and short tandem repeats (STRs). Precise and accurate gene expression measurements show relative and absolute numbers of target molecules determined independently of the number of PCR cycles. DNA methylation can be studied quantitatively. 

Tipson devoted most of his years in Levene s laboratory accomplishing seminal work on the components of nucleic acids. To determine the ring forms of the ribose component of the ribonucleosides he applied Haworth s methylation technique and established the furanoid structure for the sugar in adenosine, guanosine, uridine, and thymidine. He showed that formation of a monotrityl ether is not a reliable proof for the presence of a primary alcohol group in a nucleoside, whereas a tosyl ester that is readily displaced by iodide affords clear evidence that the ester is at the 5-position of the pentofuranose. Acetonation of ribonucleosides was shown to give the 2, 3 -C -isopropyl-idene derivatives, which were to become extensively used in nucleoside and nucleotide chemistry, and were utilized by Tipson in the first chemical preparation of a ribonucleotide, inosinic acid. 

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