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H-1 and P-31 NMR studies of oligonucleotides directed towards investigating the sequence-dependent structural nature of DNA

Thesis/Dissertation ·
OSTI ID:5671446

Assignments of the {sup 31}P resonances of a series of six sequence-related tetradecamer and two dodecamer DNA duplexes were determined by either site-specific {sup 17}O labelling of the phosphoryl groups or by two-dimensional {sup 1}H-{sup 31}P heteronuclear NMR methods. Comparisons of the {sup 31}P resonances of these sequences have allowed greater insight of various factors responsible for {sup 31}p chemical shifts in oligonucleotides. Common patterns of the {sup 31}P shift variation along the DNA duplex are shown to be sequence-dependent. The observed variation is largely a function of the purine-pyrimidine base step arrangement of the sequence. An accumulation of the {sup 31}P shift values from these sequences, as well as others presented in the literature allowed the formation of {sup 31}P shift rules, which can be used to predict the {sup 31}P NMR spectrum of other oligonucleotide sequences. Comparison of the {sup 31}P shift variation to variations in DNA helical geometry obtained from crystallographic studies of oligonucleotides in the literature indicates a sequence-dependent structural relationship exists. The {sup 31}P shifts correlate well with some geometric helical parameters, as predicted by the Dickerson/Calladine sum function rules. These correlations are consistent with the hypothesis that the structural variation is responsible for perturbing the deoxyribose phosphate backbone, which responds to changes in local helical structure. The variation of the {sup 31}P chemical shift, and the degree of this variation from one base step to the next is proposed as a potential probe of local helical conformation within the DNA double helix. Inter- and intra- nucleotide {sup 1}H-{sup 1}H distances were determined for four sequence-related tetradecamer sequences using a series of time-developed nuclear Overhauser enhancement measurements.

Research Organization:
Purdue Univ., Lafayette, IN (United States)
OSTI ID:
5671446
Country of Publication:
United States
Language:
English