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Effect of distortions in the deoxyribose phosphate backbone conformation of duplex oligodeoxyribonucleotide dodecamers containing GT, GG, GA, AC, and GU base-pair mismatches on sup 31 P NMR spectra

Journal Article · · Biochemistry; (United States)
DOI:https://doi.org/10.1021/bi00474a005· OSTI ID:5461824

The authors have previously suggested that variations in the {sup 31}P chemical shifts of individual phosphates in duplex oligonucleotides are attributable to torsional angle changes in the deoxyribose phosphate backbone. This hypothesis is now directly supported by analysis of the {sup 1}H/{sup 31}P two-dimensional J-resolved spectra of a number of mismatch dodecamer oligonucleotide duplexes including the following sequences: d(CGTGAATTCGCG), d(CGUGAATTCGCG), d(CGGGAATTCGCG), d(CGAGAATTCGCG), and d(CGCGAATTCACG). The {sup 31}P NMR signals of the dodecamer mismatch duplexes were assigned by 2D {sup 1}H/{sup 31}P pure absorption phase constant time (PAC) heteronuclear correlation spectra. From the assigned H3{prime} and H4{prime} signals, the {sup 31}P signals of the base-pair mismatch dodecamers were identified. J{sub H3{prime}-P} coupling constants for each of the phosphates of the dodecamers were obtained from {sup 1}H/{sup 31}P J-resolved selective proton flip 2D spectra. By use of a modified Karplus relationship, the C4{prime}-C3{prime}-O3{prime}-P torsional angles ({epsilon}) were obtained. J{sub H3{prime}-P} coupling constants were measured for many of the oligonucleotides as a function of temperature. The {sup 31}P chemical shifts follows the general observation that the more internally the phosphate is located within the oligonucleotide sequence, the more upfield the {sup 31}P resonance occurs. Analysis of the backbone torsional angle variations from the coupling constant analysis has provided additional information regarding the origin of these variations in {sup 31}P chemical shifts.

OSTI ID:
5461824
Journal Information:
Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 29:22; ISSN 0006-2960; ISSN BICHA
Country of Publication:
United States
Language:
English