Effects of unshared pairs of electrons and their solvation on conformational equilibria

Lemieux, R. U.

doi:10.1351/pac197125030527

Cited by 322 publications

(126 citation statements)

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“…Furthermore, it was found that ␣-glycosides (1,2-␣ ␣ cis-axial) were more labile than ␤-glyco-␤ sides (1,2-trans-equatorial). Generally it is accepted that ␣-anomers are thermodynamically more stable than ␣ ␣ ␤-anomer ␤ s [41][42][43], which is inconsistent with t t our observation in the low-energy CID process. Extensive theoretical calculations are under way to explain the phenomena.…”

Section: Erms Analysiscontrasting

confidence: 99%

Discrimination of 16 structural isomers of fucosyl galactoside based on energy-resolved mass spectrometry

Daikoku

Ako

Kato

et al. 2007

J. Am. Soc. Mass Spectrom.

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Glycans, a family of compounds often attached to proteins and ceramides, are diverse molecules involved in a wide range of biological functions. Their structural analysis is necessary and is often carried out at the microscale level. Methods based on mass spectrometry are therefore used, although they do not provide information regarding isomeric structures often found in glycan structures. If one finds "factors" characteristic of a certain isomer, this information can be used to elucidate an unknown oligosaccharide sequence. One potential technique is to use energy-resolved mass spectrometry (ERMS) that has been used to distinguish a pair of isomeric compounds. Thus, compounds in a combinatorial library might be effectively used for this purpose. We analyzed a set of 16 isomeric disaccharides, the structures of which consisted of all possible combinations of anomeric configurations and interglycosidic linkage positions. All of the compounds were distinguished based on ERMS where normal collision-induced dissociation could distinguish only seven compounds. Furthermore, it was shown that ␣-glycosidic linkages of fucose were more reactive than the ␣ ␤-isomers and the secondary glycosides were more reactive than the primary . The structural characteristics of oligosaccharides are quite different from those of other biopolymers such as nucleic acids and peptides. The diversity is generated from sequential combination in the latter two types of polymers, whereas anomers, ring size, linkage position, branching, and sequence are factors in the case of oligosaccharides [2]. Furthermore, the regulatory mechanisms for oligosaccharides still need to be clarified and synthesis, which is not template dependent, thus creates further molecular diversity called glycoforms. Despite the difficulties encountered in structural determination, there are reports on how glycosylation as a type of posttranslational modification (PTM) of protein affects glycoprotein secretion [3,4].

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Section: Erms Analysiscontrasting

confidence: 99%

Discrimination of 16 structural isomers of fucosyl galactoside based on energy-resolved mass spectrometry

Daikoku

Ako

Kato

et al. 2007

J. Am. Soc. Mass Spectrom.

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“…The ac 4 conformation, I", is also observed to predominate for some c~-methyl ribopyranoside derivatives in non-polar solvents, by reason of this bonding O(2)H-..O(4)H interaction (cf. Lemieux, 1971). * However, this is not observed in this crystal structure; neither is there any evidence for an intramolecular hydrogen bond between the syn-axial groups O(3)H to O(1)-CH3 in I', which could provide additional stability for the Ca conformer.…”

Section: Resultsmentioning

confidence: 99%

“…In both structures, the conformation observed is consistent with the orientation favored by the 'exo-anomeric effect' (cf. Lemieux, 1971;Jeffrey, Pople & Radom, 1973). The bond distances and bond angles for I and II are given in Table 3.…”

Section: Resultsmentioning

confidence: 99%

The crystal structures of methyl 5-thio-α-D-ribopyranoside and methyl 5-thio-β-D-ribopyranoside

Girling¹

1973

Acta Crystallogr Sect B

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“…It is exemplified by the effect of solvent on the 4C 1 ~ 1C4 pyranoside equilibrium shown below, as postulated by Lemieux (1971) from optical and n.m.r, studies.…”

Section: The Crystal Environment Of the Gluconate Ionmentioning

confidence: 88%

The crystal structures of the A and B forms of potassium D-gluconate monohydrate by neutron diffraction

Panagiotopoulos¹,

Placa²,

Hamilton³

1974

Acta Crystallogr Sect B

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Effects of unshared pairs of electrons and their solvation on conformational equilibria

Abstract: Abstract

Cited by 322 publications

References 0 publications

Discrimination of 16 structural isomers of fucosyl galactoside based on energy-resolved mass spectrometry

Discrimination of 16 structural isomers of fucosyl galactoside based on energy-resolved mass spectrometry

The crystal structures of methyl 5-thio-α-D-ribopyranoside and methyl 5-thio-β-D-ribopyranoside

The crystal structures of the A and B forms of potassium D-gluconate monohydrate by neutron diffraction

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