Note on the Solubility of Indigo in Dimethyl Sulphate.

2008 ◽  
Vol 30 (3) ◽  
pp. 84-85
Author(s):  
S. J. PEACHEY
Keyword(s):  
Dimethyl Sulphate

scholarly journals Methylation of deoxyribonucleic acid in cultured mammalian cells by N-methyl-N′-nitro-N-nitrosoguanidine. The influence of cellular thiol concentrations on the extent of methylation and the 6-oxygen atom of guanine as a site of methylation

1970 ◽  
Vol 116 (4) ◽  
pp. 693-707 ◽  
Author(s):  
P. D. Lawley ◽  
Carolyn J. Thatcher
Keyword(s):  
Oxygen Atom ◽  
Nucleic Acids ◽  
Mammalian Cells ◽  
Dimethyl Sulphate ◽  
Biological Effects ◽  
Methylation Of Dna ◽  
Thiol Content ◽  
Cellular Thiol ◽  
In Cells

1. In neutral aqueous solution N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) yields salts of nitrocyanamide as u.v.-absorbing products. With cysteine, as found independently by Schulz & McCalla (1969), the principal product is 2-nitràminothiazoline-4-carboxylic acid. Both these reactions liberate the methylating species; thiols enhance the rate markedly at neutral pH values. An alternative reaction with thiols gives cystine, presumably via the unstable S-nitrosocysteine. 2. Thiols (glutathione or N-acetylcysteine) in vitro at about the concentration found in mammalian cells enhance the rate of methylation of DNA markedly over that in neutral solution. 3. Treatment of cultured mammalian cells with MNNG results in rapid methylation of nucleic acids, the extent being greater the higher the thiol content of the cells. Rodent embryo cells are more extensively methylated than mouse L-cells of the same thiol content. Cellular thiol concentrations are decreased by MNNG. Proteins are less methylated by MNNG than are nucleic acids. 4. Methylation of cells by dimethyl sulphate does not depend on cellular thiol content and protein is not less methylated than nucleic acids. Methylation by MNNG may therefore be thiol-stimulated in cells. 5. Both in vitro and in cells about 7% of the methylation of DNA by MNNG occurs at the 6-oxygen atom of guanine. The major products 7-methylguanine and 3-methyladenine are given by both MNNG and dimethyl sulphate, but dimethyl sulphate does not yield O6-methylguanine. Possible reaction mechanisms to account for this difference between these methylating agents and its possible significance as a determinant of their biological effects are discussed.

scholarly journals Alkylation of deoxyribonucleic acid by carcinogens dimethyl sulphate, ethyl methanesulphonate, N-ethyl-N-nitrosourea and N-methyl-N-nitrosourea. Relative reactivity of the phosphodiester site thymidylyl(3′-5′)thymidine

1978 ◽  
Vol 171 (3) ◽  
pp. 575-587 ◽  
Author(s):  
D H Swenson ◽  
P D Lawley
Keyword(s):  
Alkyl Group ◽  
Deoxyribonucleic Acid ◽  
Dimethyl Sulphate ◽  
Alkylating Agents ◽  
Electrophilic Reagent ◽  
Relative Reactivity ◽  
Ethyl Methanesulphonate ◽  
A Value ◽  
Phosphodiester Group ◽  
Steric Accessibility

1. The ethyl phosphotriester of thymidylyl(3′-5′)thymidine, dTp(Et)dT, was identified as a product from reaction of DNA with N-ethyl-N-nitrosourea, by procedures parallel to those reported previously for the methyl homologue produced by N-methyl-N-nitrosourea. 2. Enzymic degradation to yield alkyl phosphotriesters from DNA alkylated by these carcinogens and by dimethyl sulphate and ethyl methanesulphonate was studied quantitatively, and the relative yields of the triesters dTp(Alk)dT were determined. The relative reactivity of the phosphodiester group dTpdT to each of the four carcinogens was thus obtained, and compared with that of DNA overall, or with that of the N-7 atom of guanine in DNA. Relative reactivity of the phosphodiester group was lowest towards dimethyl sulphate, the least electrophilic of the reagents used, and was highest towards N-ethyl-N-nitrosourea, the most electrophilic reagent. 3. The nature of the alkyl group transferred also influenced reactivity of the phosphodiester site, since this site was relatively more reactive towards ethylation than would be predicted simply from the known Swain-Scott s values of the alkylating agents. It was therefore suggested that the steric accessibility of the weakly nucleophilic phosphodiester group on the outside of the DNA macromolecule favours its reaction with ethylating, as opposed to methylating, reagents. 4. Taking a value of the Swain-Scott nucleophilicity (n) of 2.5 for an average DNA nucleotide unit [Walles & Ehrenberg (1969) Acta Chem. Scand. 23, 1080-1084], a value of n of about 1 for the phosphodiester group was deduced, and this value was found to be 2-3 units less than that for the N-7 atom of guanine in DNA. 5. The reactivity of DNA overall was markedly high towards the alkylnitrosoureas, despite their relatively low s values. This was ascribed to an electrostatic factor that favoured reaction of the negatively charged polymer with alkyldiazonium cation intermediates.

Angular Heterocyclics: Studies in the Synthesis of Some Substituted 6-Anilino-5-alkoxy-12 H-benzo [a] phenothiazines

1978 ◽  
Vol 33 (2) ◽  
pp. 214-215 ◽  
Author(s):  
J. P. Tiwari ◽  
R. L. Mital
Keyword(s):  
Dimethyl Sulphate ◽  
Reaction Path

6-Anilino-12H-benzo[a]phenothiazin-5-ol reacts with dimethyl sulphate or 2-bromopropane to give 6-anilino-5-alkoxy (methoxy/isopropoxy)-12H-benzo[a]phenothiazine. Synthesis of various 9,11-disubstituted analogues have been described. A common reaction path is suggested

Flavonoid intermediates for the synthesis of mopanol trimethyl ether[trans-trans-7,7',8'-Trimethoxyisochromano(4',3':2,3)chroman-4-ol]

1976 ◽  
Vol 29 (1) ◽  
pp. 191 ◽  
Author(s):  
JW Clark-Lewis ◽  
DP Cox
Keyword(s):  
Carboxylic Acid ◽  
Potassium Carbonate ◽  
Dimethyl Sulphate ◽  
Metal Hydrides ◽  
Cyclic Ether ◽  
Protecting Group ◽  
Model Compounds ◽  
Initial Product ◽  
Dibenzyl Ether ◽  
Trimethyl Ether

Preparation of a number of intermediates for the synthesis of (�)-mopanol trimethyl ether is described, together with exploratory reactions with model compounds, and especially with 7-methoxyflavanone-2'-carboxylic acid. 7-Methoxyflavan-4-ol, the initial product from reduction of 7-methoxyflavanone-2'-carboxylic acid with complex metal hydrides, was found to undergo facile dehydration to a novel intramolecular dibenzyl ether [the cyclic ether (19)*]. It was noted that the methoxymethyl group, which may be used as a protecting group for phenols, did not survive the conditions of methylation with dimethyl sulphate and potassium carbonate in acetone.

Sign in / Sign up

Export Citation Format

Share Document