Measurement of Long Range 1H-19F Scalar Coupling Constants and their Glycosidic Torsion Dependence in 5-Fluoropyrimidine Substituted RNA.
| Title in English | Three-Bond Sugar-Base Couplings in Purine versus Pyrimidine Nucleosides: A DFT Study of Karplus Relationships for 3JC2/4-H1' and 3JC6/8-H1' in DNA |
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| Authors | |
| Year of publication | 2006 |
| Type | Article in Periodical |
| Magazine / Source | Journal of the American Chemical Society |
| MU Faculty or unit | |
| Citation | |
| Field | Physical chemistry and theoretical chemistry |
| Keywords | Scalar Coupling Constants; Fluorine; 5-Fluorouridine; 5-Fluorocytidine; HIV-TAR RNA |
| Description | Long range scalar 5J(H1',F) couplings were observed in 5-fluoropyrimidine substituted RNA. We developed a novel S3E-19F-alfa/beta-edited NOESY experiment for quantitation of these long range scalar 5J(H1',F), where the J-couplings can be extracted from inspection of intraresidual (H1',H6) NOE crosspeaks. The 5J(H1',F) couplings can be used to restrict the glycosidic torsion angle which defines the orientation of the base with respect to the ribose sugar moiety. Quantum chemical calculations were exploited to investigate the relation between scalar couplings and conformations around the glycosidic bond in oligonucleotides. The theoretical dependence of the observed 5J(H1',F) couplings on the torsion angle Ó can be described by a generalized Karplus relationship. The corresponding density functional theory (DFT) analysis is outlined. Additional NMR experiments facilitating the resonance assignments of 5-fluoropyrimidine substituted RNAs are described and chemical shift changes due to altered shielding in the presence of fluorine-19 (19F) are presented. |
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