Dataset Information

Interplay of Protecting Groups and Side Chain Conformation in Glycopyranosides. Modulation of the Influence of Remote Substituents on Glycosylation?

ABSTRACT: The synthesis and conformational analysis of a series of phenyl 2,3,6-tri- O-benzyl-?-d-thio galacto- and glucopyranosides and their 6 S-deuterio isotopomers, with systematic variation of the protecting group at the 4-position, are described. For the galactopyranosides, replacement of a 4- O-benzyl ether by a 4- O-alkanoyl or aroyl ester results in a small but measurable shift in side chain population away from the trans, gauche conformation and in favor of the gauche, trans conformer. In the glucopyranoside series on the other hand, replacement of a 4- O-benzyl ether by a 4- O-alkanoyl or aroyl ester results in a small but measurable increase in the population of the trans, gauche conformer at the expense of the gauche, gauche conformer. The possible modulating effect of these conformational changes on the well-known changes in the anomeric reactivity of glycosyl donors as a function of protecting group is discussed, raising the possibility that larger changes may be observed at the transition state for glycosylation. A comparable study with a series of ethyl 2,3,4-tri- O-benzyl-?-d-thioglucopyranosides reveals that no significant influence in side chain population is observed on changing the O6 protecting group.

SUBMITTER: Dharuman S

PROVIDER: S-EPMC6131524 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Interplay of Protecting Groups and Side Chain Conformation in Glycopyranosides. Modulation of the Influence of Remote Substituents on Glycosylation?

Dharuman Suresh S Amarasekara Harsha H Crich David D

The Journal of organic chemistry 20180822 17

The synthesis and conformational analysis of a series of phenyl 2,3,6-tri- O-benzyl-β-d-thio galacto- and glucopyranosides and their 6 S-deuterio isotopomers, with systematic variation of the protecting group at the 4-position, are described. For the galactopyranosides, replacement of a 4- O-benzyl ether by a 4- O-alkanoyl or aroyl ester results in a small but measurable shift in side chain population away from the trans, gauche conformation and in favor of the gauche, trans conformer. In the gl ...[more]

PMID: 30063354

Similar Datasets

Project description:A series of designed peptides has been analyzed by 1H-NMR spectroscopy in order to investigate the influence of cross-strand side-chain interactions in beta-hairpin formation. The peptides differ in the N-terminal residues of a previously designed linear decapeptide that folds in aqueous solution into two interconverting beta-hairpin conformations, one with a type I turn (beta-hairpin 4:4) and the other with a type I + G1 beta-bulge turn (beta-hairpin 3:5). Analysis of the conformational behavior of the peptides studied here demonstrates three favorable and two unfavorable cross-strand side-chain interactions for beta-hairpin formation. These results are in agreement with statistical data on side-chain interactions in protein beta-sheets. All the peptides in this study form significant populations of the beta-hairpin 3:5, but only some of them also adopt the beta-hairpin 4:4. The formation of beta-hairpin 4:4 requires the presence of at least two favorable cross-strand interactions, whereas beta-hairpin 3:5 seems to be less susceptible to side-chain interactions. A protein database analysis of beta-hairpins 3:5 and beta-hairpins 4:4 indicates that the former occur more frequently than the latter. In both peptides and proteins, beta-hairpins 3:5 have a larger right-handed twist than beta-hairpins 4:4, so that a factor contributing to the higher stability of beta-hairpin 3:5 relative to beta-hairpin 4:4 is due to an appropriate backbone conformation of the type I + G1 beta-bulge turn toward the right-handed twist usually observed in protein beta-sheets. In contrast, as suggested previously, backbone geometry of the type I turn is not adequate for the right-handed twist. Because analysis of buried hydrophobic surface areas on protein beta-hairpins reveals that beta-hairpins 3:5 bury more hydrophobic surface area than beta-hairpins 4:4, we suggest that the right-handed twist observed in beta-hairpin 3:5 allows a better packing of side chains and that this may also contribute to its higher intrinsic stability.

Dataset Information

Interplay of Protecting Groups and Side Chain Conformation in Glycopyranosides. Modulation of the Influence of Remote Substituents on Glycosylation?

Publications

Interplay of Protecting Groups and Side Chain Conformation in Glycopyranosides. Modulation of the Influence of Remote Substituents on Glycosylation?

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets