Bdour HM, Kao JLF, Taylor JS. Synthesis and characterization of a [3-15N]-labeled cis-syn thymine dimer-containing DNA duplex.
J Org Chem 2006;
71:1640-6. [PMID:
16468818 PMCID:
PMC2580729 DOI:
10.1021/jo0524167]
[Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Cis-syn thymine dimers are the major photoproducts of DNA and are the principal cause of mutations induced by sunlight. To better understand the nature of base pairing with cis-syn thymine dimers, we have synthesized a decamer oligodeoxynucleotide (ODN) containing a cis-syn thymine dimer labeled at the N3 of both T's with 15N by two efficient routes from [3-15N]-thymidine phosphoramidite. In the postsynthetic irradiation route, an ODN containing an adjacent pair of [3-15N]-labeled T's was irradiated and the cis-syn dimer-containing ODN isolated by HPLC. In the mixed building block route, a mixture of cis-syn and trans-syn dimer-containing ODNs was synthesized from a mixture of [3-15N]-labeled thymine dimer phosphoramidites after which the cis-syn dimer-containing ODN was isolated by HPLC. The N3-nitrogen and imino proton signals of an (15)N-labeled thymine dimer-containing decamer duplex were assigned by 2D 1H-15N heterocorrelated HSQC NMR spectroscopy, and the 15N-1H coupling constant was found to be 1.8 Hz greater for the 5'-T than for the 3'-T. The larger coupling constant is indicative of weaker H-bonding that is consistent with the more distorted nature of the 5'-base pair found in solution state NMR and crystallographic structures.
Collapse