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Enzymatic methylation of DNA and poly(dG—dC) · poly(dG—dC) modified by 4-acetoxyaminoquinoline-1-oxide, the ultimate carcinogen of 4-nitroquinoline-1-oxide

Authors
Journal
FEBS Letters
0014-5793
Publisher
Wiley Blackwell (John Wiley & Sons)
Publication Date
Volume
163
Issue
1
Identifiers
DOI: 10.1016/0014-5793(83)81169-7
Keywords
  • Dna Methylation
  • 4-Nitroquinoline-Oxide
  • Dna(Cytosine-5-)-Methyltransferase
  • Brain
  • Poly(Dg-Dc) · Poly(Dg-Dc)
  • Chemical Carcinogen
Disciplines
  • Biology

Abstract

Abstract Both the initial velocity and the overall methylation of Ac-4HAQO modified DNA by a calf brain DNA (cytosine-5-)-methyltransferase are increased as compared to native DNA. The affinity of the modified DNA for the enzyme decreases as a function of the extent of the modification. Heat-denatured, single-stranded DNA shows exactly the opposite results; the more it is modified, the less it is methylated. The poly(dG—dC) · poly(dG—dC) modified by 4NQO is as well methylated as the non-modified one. The carcinogen may induce a tertiary structure favouring the ‘walking’ of the enzyme along the DNA. The hypermethylation caused by this carcinogen could have a significance in gene activity and cellular differentiation.

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