Synthesis and characterization of oligonucleotides containing 5-chlorocytosine

Joseph I. Kang, Artur Burdzy, Pingfang Liu, Lawrence Sowers

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Recent studies have shown that reactive chlorine species, derived from myeloperoxidase-mediated inflammation responses, can modify DNA bases, generating 5-chloropyrimidines. The chlorinated adducts could be mutagenic or perturb DNA-protein interactions; however, the biological significance of these adducts is as yet unknown. We report here a method for the synthesis of 5-chlorocytosine- (ClC-) containing oligonucleotides that will be used in subsequent biochemical and biophysical studies to determine the consequences of pyrimidine chlorination. The ClC-phosphoramidite synthon is obtained by chlorination of 2′-deoxyuridine followed by conversion to the O 4-ethyl analogue. The amino group needed to form the corresponding cytosine derivative is added by displacement of the O4-ethyl group during ammonia deprotection. A battery of methods, including mass spectrometry, has been used to characterize oligonucleotides containing ClC. Following oligonucleotide synthesis and deprotection, only trace amounts of the deamination product 5-chlorouracil can be detected by enzymatic cleavage of duplex oligonucleotides with the mispaired uracil glycosylase, MUG. In contrast to previous reports, we find that ClC is more stable in DNA than anticipated. Approximately 20% ClC is lost under standard formic acid hydrolysis conditions (88% formic acid, 140 °C, 30 min), while only 5% is recovered as 5-chlorouracil (ClU).

Original languageEnglish (US)
Pages (from-to)1236-1244
Number of pages9
JournalChemical Research in Toxicology
Volume17
Issue number9
DOIs
StatePublished - Sep 2004
Externally publishedYes

Fingerprint

formic acid
Oligonucleotides
Chlorination
Halogenation
DNA
Deoxyuridine
Deamination
Uracil
Cytosine
Chlorine
Ammonia
Peroxidase
Mass spectrometry
Hydrolysis
Mass Spectrometry
Inflammation
Derivatives
5-chlorocytosine
Proteins
5-chlorouracil

ASJC Scopus subject areas

  • Drug Discovery
  • Organic Chemistry
  • Chemistry(all)
  • Toxicology
  • Health, Toxicology and Mutagenesis

Cite this

Synthesis and characterization of oligonucleotides containing 5-chlorocytosine. / Kang, Joseph I.; Burdzy, Artur; Liu, Pingfang; Sowers, Lawrence.

In: Chemical Research in Toxicology, Vol. 17, No. 9, 09.2004, p. 1236-1244.

Research output: Contribution to journalArticle

Kang, Joseph I. ; Burdzy, Artur ; Liu, Pingfang ; Sowers, Lawrence. / Synthesis and characterization of oligonucleotides containing 5-chlorocytosine. In: Chemical Research in Toxicology. 2004 ; Vol. 17, No. 9. pp. 1236-1244.
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