Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1970-5-4
pubmed:abstractText
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 O(6)-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.
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-13459887, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-13824776, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-13853711, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-13911600, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-13937132, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-14097355, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-14240664, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-14292263, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-14462974, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-4226178, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-4890603, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-5637372, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-5647053, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-5655187, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-5672862, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-5722690, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-5779633, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-5783466, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-5791738, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-5835618, http://linkedlifedata.com/resource/pubmed/commentcorrection/5435496-5912421
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0264-6021
pubmed:author
pubmed:issnType
Print
pubmed:volume
116
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
693-707
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1970
pubmed:articleTitle
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.
pubmed:publicationType
Journal Article, In Vitro