Conformational studies of α- and β-pyrimidine 2′-deoxyribonucleosides in the syn and anti conformation

Cadet, Jean; Taieb, C.; Remin, Mieczyslaw; Niemczura, Walter P.; Hruska, Frank E.

doi:10.1016/0005-2787(80)90189-6

Cited by 39 publications

(26 citation statements)

References 37 publications

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“…A "mirror" pattern of behavior of chemical shifts refers to ␣-anomers. Using ␣-thymidine as an anti model and ␣-6-methyl 2Ј-deoxyuridine as a syn model, the conformational change from anti to syn, leads to a large downfield (0.52 ppm) displacement of the cis H2Љ proton and a much smaller upfield (0.03 ppm) shift of the trans H2Ј proton (29). A similar pattern of behavior is observed in all ␣-anomers of this series (Table 1).…”

Section: Conformation About Glycosidic Bondsupporting

confidence: 69%

“…Thus a considerable preference of S over N in ␤-anomers and a very strong preference in ␣-anomers is a characteristic property of these 2Ј-deoxynucleosides when they are in anti conformation. In opposition, N is preferred in 6-methyluridine, 64%, in ␤-anomer, and in a greater extent, 81%, in ␣-anomer (29). Thus a considerable preference of N over S in ␤-anomers and a very strong preference in ␣-anomers is a characteristic property of these 2Ј-deoxynucleosides when they are in syn conformation.…”

Section: Figmentioning

confidence: 85%

“…Also in other members of this series as well as in a large series of 5-substituted 2Ј-deoxyribonucleosides, H2Ј and H2Љ lie usually in relatively narrow ranges, 2.32-2.42 ppm and 2.37-2.48 ppm, respectively (14). Using thymidine as an anti model and 6-methyl 2Ј-deoxyuridine as a syn model, the conformational change from anti to syn, leads to a large downfield (0.57 ppm) displacement of the cis H2Ј proton and a much smaller upfield (0.12 ppm) shift of the trans H2Љ proton (29). A similar pattern of behavior is observed in all ␤-anomers of this series (Table 1).…”

Section: Conformation About Glycosidic Bondmentioning

confidence: 98%

“…Such a description is especially justified in case of pyrimidine nucleosides where, mainly due to C(2)OO carbonyl group, there are two significant barriers for the rotation about glycosidic bond (31). A thorough stereochemical considerations for model ␣-and ␤-pyrimidine 2Ј-deoxyribonucleosides in the anti and syn conformation, have been presented (29). They provide a basis for comparative conformational analysis of chemical shifts of the two protons, H2Ј and H2Љ, in ␣-and ␤-anomers of this series of compounds, as presented in Table 1.…”

Section: Conformation About Glycosidic Bondmentioning

confidence: 98%

“…Due to this, the behavior of their chemical shifts in ␣-and ␤-anomers shows a "mirror" pattern and provides a sensitive probe for studying the conformation of the base. To a first approximation, cis H2Ј in ␤-anomer, and cis H2Љ in ␣-anomer, on one hand, and trans H2Љ in ␤-anomer, and trans H2Ј in ␣-anomer, on the other hand, receive a similar shielding from the base with a given conformation i.e., anti or syn (29).…”

Section: Conformation About Glycosidic Bondmentioning

confidence: 99%

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1H NMR Conformational Study of a Variety of α-Anomers of C5-Substituted 2′-Deoxyuridines: Comparison to Their Antiherpetic β Counterparts

Poznański

Felczak

Bretner

et al. 2001

Biochemical and Biophysical Research Communications

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Section: Conformation About Glycosidic Bondsupporting

confidence: 69%

Section: Figmentioning

confidence: 85%

Section: Conformation About Glycosidic Bondmentioning

confidence: 98%

Section: Conformation About Glycosidic Bondmentioning

confidence: 98%

Section: Conformation About Glycosidic Bondmentioning

confidence: 99%

See 3 more Smart Citations

1H NMR Conformational Study of a Variety of α-Anomers of C5-Substituted 2′-Deoxyuridines: Comparison to Their Antiherpetic β Counterparts

Poznański

Felczak

Bretner

et al. 2001

Biochemical and Biophysical Research Communications

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Proton magnetic resonance study of nucleosides, nucleotides, and dideoxynucleoside monophosphates containing a syn pyrimidine base

Niemczura¹,

Hruska²,

Sadana³

et al. 1981

Biopolymers

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Proton magnetic resonance data have been obtained for 6‐methyl‐2′‐deoxyuridine (dT*), its 3′‐ and 5′‐monophosphates, and its 3′,5′‐diphosphate, as well as for the corresponding thymine derivatives. The synthesis of the dideoxynucleoside monophosphates—d(TpT), d(T*pT), d(TpT*), and d(T*pT*)—was accomplished, and spectral data were obtained for these four dimers. The data show that the 6‐methyluracil base prefers the syn conformation about the N‐glycosyl bond at the monomer and dimer levels. The presence of the syn base leads to increases in the cis couplings of the sugar ring, J1′2″ and J2′3′, which indicate a trend towards eclipsing of the substituents on the C1′‐C2′ and C2′‐C3′ fragments. This trend is discussed in terms of changes in the pseudorotational parameters which describe the pucker of the ring. The syn base destabilizes the g+ conformer about the C4′‐C5′ bond, leading to a preference for the t conformer in all dT* residues at the monomer and dimer levels. Preliminary work on the formation of cyclobutane‐type photodimers in d(T*pT) and d(T*pT*) is discussed and presented as evidence for the capability of the syn 6‐methyluracil base to form base‐stacked complexes.

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Stereochemical studies on nucleic acid analogues. I. Conformations of α‐nucleosides and α‐nucleotides: Interconversion of sugar puckers via O4′‐exo

Latha

Yathindra

1992

Biopolymers

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The preferred conformations of ribo and deoxyribo alpha-nucleosides and alpha-nucleotides, the stereoisomers of the naturally occurring beta-isomers, are worked out by minimizing the conformational energy as a function of all the major parameters including the sugar ring conformations along the pseudorotation path. The results of the studies bring out certain distinct conformational features that are at variance with their beta counterparts. The range of glycosyl conformations are found to be not only quite restricted here but favor predominantly the anti conformation. The syn glycosyl conformation for the entire region of P values are found to be energetically less favorable, with the barrier to anti in equilibrium with syn interconversion being higher especially in alpha-ribonucleosides. The energetically preferred range of pseudorotation phase angles (P) is also considerably restricted and P values corresponding to the C1'-exo range of sugars are highly unfavorable for alpha-nucleosides, in sharp contrast to the broad range of sugar ring conformations favored by beta-isomers. While both trans congruent to 180 degrees and skew congruent to 270 degrees conformations around the C3'-O3' (phi') bond are favored for alpha-3'-nucleotides with deoxyribose sugars, ribose sugars seem to favor only the skew values of phi'. Most interestingly and in sharp contrast to beta-stereoisomers, an energy barrier is encountered at P values corresponding to O4'-endo sugars. This suggests that the possible sugar pucker interconversion between C2'-endo/C3'-exo and C3'-endo/C2'-exo in alpha-anomers could take place only through the O4'-exo region. Likewise the possible path of anti in equilibrium with syn interconversion in alpha-nucleosides is not via high anti, in sharp contrast to beta-nucleosides. These observations should be borne in mind while assigning the sugar ring conformers in alpha-nucleosides and those containing them from nmr investigations. Comparison of the results with beta-anomers seem to suggest on the whole a lack of conformational variability or the restricted nature of alpha-stereoisomers. This could be one of the reasons for its nonselection in the naturally occurring nucleic acids.

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Conformational studies of α- and β-pyrimidine 2′-deoxyribonucleosides in the syn and anti conformation

Cited by 39 publications

References 37 publications

1H NMR Conformational Study of a Variety of α-Anomers of C5-Substituted 2′-Deoxyuridines: Comparison to Their Antiherpetic β Counterparts

1H NMR Conformational Study of a Variety of α-Anomers of C5-Substituted 2′-Deoxyuridines: Comparison to Their Antiherpetic β Counterparts

Proton magnetic resonance study of nucleosides, nucleotides, and dideoxynucleoside monophosphates containing a syn pyrimidine base

Stereochemical studies on nucleic acid analogues. I. Conformations of α‐nucleosides and α‐nucleotides: Interconversion of sugar puckers via O4′‐exo

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