Internucleotide Scalar Couplings Across Hydrogen Bonds in Watson-Crick and Hoogsteen Base Pairs of a DNA Triplex
详细信息 查看全文
- 作者：Andrew J. Dingley ; James E. Masse ; Robert D. Peterson ; Michael Barfield ; Juli Feigon ; and Stephan Grzesiek
- 刊名：Journal of the American Chemical Society
- 出版年：1999
- 出版时间：June 30, 1999
- 年：1999
- 卷：121
- 期：25
- 页码：6019 - 6027
- 全文大小：130K
- 年卷期：v.121,no.25(June 30, 1999)
- ISSN：1520-5126
文摘
An extensive analysis of trans-hydrogen bond 2hJNN and 1hJHN scalar couplings, the covalent 1JHNcouplings, and the imino proton chemical shifts is presented for Hoogsteen-Watson-Crick T
A-T andC+G-C triplets of an intramolecular DNA triplex. The 2hJNN coupling constants for the Watson-Crick basepairs have values ranging from 6 to 8 Hz, while the Hoogsteen base paired thymines and protonated cytidineshave values of approximately 7 and 10 Hz, respectively. Distinct decreases of 2hJNN are observed at the triplexstrand ends. Trans-hydrogen bond J correlations (1hJHN) between the donor 1H nucleus and the acceptor 15Nnucleus are observed for this triplex by a novel, simple quantitative J-correlation experiment. These one-bond1hJHN couplings range between 1 and 3 Hz. A strong correlation is found between the chemical shift of theimino proton and the size of 2hJNN, with stronger J couplings corresponding to downfield chemical shifts. Asimilar, but inverse correlation is found between the proton chemical shift and the (absolute) size of the covalent1JHN constant. Methods of density functional theory were used to investigate the structural requirements forscalar J coupling and magnetic shielding associated with hydrogen bonding in nucleic acid base pairs. Thedependencies of these NMR parameters on hydrogen bond distances were obtained for a representative basepair fragment. The results reproduce the trans-hydrogen bond coupling effect and the experimental correlationsand suggest that the NMR parameters can be used to gain important insight into the nature of the hydrogenbond.
A-T andC+G-C triplets of an intramolecular DNA triplex. The 2hJNN coupling constants for the Watson-Crick basepairs have values ranging from 6 to 8 Hz, while the Hoogsteen base paired thymines and protonated cytidineshave values of approximately 7 and 10 Hz, respectively. Distinct decreases of 2hJNN are observed at the triplexstrand ends. Trans-hydrogen bond J correlations (1hJHN) between the donor 1H nucleus and the acceptor 15Nnucleus are observed for this triplex by a novel, simple quantitative J-correlation experiment. These one-bond1hJHN couplings range between 1 and 3 Hz. A strong correlation is found between the chemical shift of theimino proton and the size of 2hJNN, with stronger J couplings corresponding to downfield chemical shifts. Asimilar, but inverse correlation is found between the proton chemical shift and the (absolute) size of the covalent1JHN constant. Methods of density functional theory were used to investigate the structural requirements forscalar J coupling and magnetic shielding associated with hydrogen bonding in nucleic acid base pairs. Thedependencies of these NMR parameters on hydrogen bond distances were obtained for a representative basepair fragment. The results reproduce the trans-hydrogen bond coupling effect and the experimental correlationsand suggest that the NMR parameters can be used to gain important insight into the nature of the hydrogenbond.