Abstract
The conformation and internal dynamics of the octadeoxynucleotide d(CACTAGTG)2 have been examined by 1H- and 13C-n.m.r. relaxation. All the non-exchangeable protons, the seven phosphate resonances, and most of the 13C resonances of the proton-bearing carbons have been assigned by conventional two-dimensional n.m.r. methods. The average conformations of each nucleotide have been determined using time-dependent one-dimensional n.O.e.'s and 3JHH values derived from both NOESY and 2-quantum-filtered COSY experiments. All glycosidic torsion angles are anti, and in the range -95 to 125°, in which the pyrimidines have a significantly larger angle than the purines. All sugars were found mainly (> 80%) in the conformation range C-2′ endo to C-3′exo. The DNA fragment is within the B-family of conformations. The cytosine H-6-H-5 vectors move with an apparent correlation time of 3 ns at 25°. Cross-relaxation rate constants for the H-1′-H-2b vectors and some H-2a-H-2b and H-2a-H-3′ vectors were measured, from which order parameters were determined. The order parameters are all in the range 0.7-0.9, which is consistent with only moderate internal mobility on the sub-ns time scale. The {1H}-13C n.O.e. and the spin-lattice relaxation rate constant show that the terminal residues are relatively more mobile than the internal residues, and that the C-2′-H and C-3′%z.sbnd;-H vectors move with order parameters of 0.6-0.75.
Original language | English |
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Pages (from-to) | 123-144 |
Number of pages | 22 |
Journal | Carbohydrate Research |
Volume | 221 |
Issue number | 1 |
DOIs | |
State | Published - Dec 16 1991 |
Bibliographical note
Funding Information:This work was supported by the Medical Research Council. for the purification of the oligonucleotide, and Dr. J. Feeney for
ASJC Scopus subject areas
- Analytical Chemistry
- Biochemistry
- Organic Chemistry