Two-bond 13C-13C spin-coupling constants in carbohydrates: effect of structure on coupling magnitude and sign

Church, Timothy; Carmichael, Ian; Serianni, Anthony S.

doi:10.1016/0008-6215(95)00311-8

Cited by 54 publications

(79 citation statements)

References 26 publications

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“…These results provide experimental confirmation of the (AMX) which includes the coupling constant whose sign is under investigation and a 1 J CC and/or 3 J CC value of known 2 J CCC and 2 J COC sign predictions made by the projection resultant method (14) and provide the first experimental positive sign as an internal reference. However, selective 13 C-labeling is not required for these determinations.…”

supporting

confidence: 64%

Verification of the Projection Resultant Method for Two-Bond13C–13C Coupling Sign Determinations in Carbohydrates

Serianni

Bondo²,

Zajíček

1996

Journal of Magnetic Resonance, Series B

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supporting

confidence: 64%

Verification of the Projection Resultant Method for Two-Bond13C–13C Coupling Sign Determinations in Carbohydrates

Serianni

Bondo²,

Zajíček

1996

Journal of Magnetic Resonance, Series B

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“…In recent years the value of long-range 13C-13C coupling constants for the conformational analysis of oligosaccharides has been realized [52][53][54][55][56][57][58]. A principal difficulty with the measurement of these parameters is the requirement for 13C-enriched material-unlike heteronuclear 13C-' H measurements where the -1% natural abundance of I3C is not a substantial sensitivity barrier, 0.01% of 954 33 Conformational Analysis in Solution by NMR molecules will contain two 13C nuclei.…”

Section: ~-' 3~ Coupling-constantsmentioning

confidence: 99%

Conformational Analysis in Solution by NMR

Homans¹

2000

Carbohydrates in Chemistry and Biology

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Of the functions that have been ascribed to oligosaccharides [ 11, their role in molecular recognition appears to be a repetitive theme in many biological processes. Recent work on the molecular genetics of glycosylation has indicated that oligosaccharides exhibit a particularly prominent role in the development of multicellular organisms [2-91. Morever, it has been known for many years that oligosaccharides are important for the invasion, infectivity and survival of parasites [ 101 and pathogens [ 111 in host cells. There is therefore compelling evidence to suggest that a role in cell-cell communication might be the primary function of oligosaccharides. This might explain the apparent lack of function of these moieties when examined at the level of a protein or indeed an individual cell.In order to understand the molecular basis of oligosaccharide-mediated recognition phenomena, we need to have knowledge of the structure and dynamics of the free carbohydrate ligand in addition to the ligand-receptor complex. In this Chapter, I shall review current knowledge on the former. A discussion of ligand-receptor complexes can be found elsewhere in this volume. Solution Conformations of Oligosaccharides The NMR TechniqueSince oligosaccharides in general fail to crystallize, the only technique that is able reliably to offer information on the structure of oligosaccharides in solution at atomic resolution is nuclear magnetic resonance (NMR) spectroscopy [ 12-1 51. There are three NMR parameters that are relevant to the structural analysis of oli- Carbohydrates in Chemistry

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“…First, the projection sums were calculated from the cosine dependence given by Church et al (21) for the different glycosidic linkages which occur in the polysaccharide of Chart 1. The projection resultants were related to the coupling constants using the data of Scheme 6 in ref 21, producing the approximate correlation illustrated in Figure 1.…”

Section: Chart 1: S Mitis J22 Polysaccharidementioning

confidence: 99%

New Strategy for the Conformational Analysis of Carbohydrates Based on NOE and ¹³C NMR Coupling Constants. Application to the Flexible Polysaccharide of Streptococcus mitis J22

Martín-Pastor

Bush

1999

Biochemistry

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For complex oligosaccharides, which are relatively rigid with modest excursions from a single minimum energy conformation, it is straightforward to build conformational models from NOE data. Other oligosaccharides are more flexible with transitions between distinct minima separated by substantial energy barriers. We show that modeling based on scalar coupling data is superior to NOE-based modeling for the latter case. Long range 13 C-13 C and 13 C-1 H coupling constants measured for the heptasaccharide repeating subunit of the cell wall polysaccharide from Streptococcus mitis J22 are correlated with individual glycosidic dihedral angles, effectively uncoupling the degrees of freedom of the oligosaccharide and allowing a search for combinations of dihedral angles which are energetically reasonable, i.e., with no bad van der Waals contacts, and which can be combined to satisfy all the measured J values. Allowed values of the individual angles can then be combined to search for overall oligosaccharide conformations which contribute to the ensemble. We show that while the polysaccharide from S. mitis J22 is flexible, requiring multiple conformations, most of the flexibility is localized to a few bonds and only a rather small number of conformations is required to reproduce the experimental NOE and scalar coupling data.A central question in the conformation and dynamics of complex oligosaccharides and polysaccharides is whether a given structure is "flexible" (1-3). In fact, no oligosaccharide is likely to be truly rigid since puckering of the pyranoside ring and fluctuations of the glycosidic dihedral angles must occur to some extent in all cases. But the currently available data allows for classification of the types of internal motion in oligosaccharides into two distinct types. We will identify internal motion of the first kind as rapid motion on a picosecond time scale of the internal degrees of freedom within a local minimum with limited excursions of the dihedral angles. Oligosaccharides exhibiting this type of internal motion are sometimes called "rigid" in the sense that experimental NOE 1 data may agree with that calculated for a model having a single conformation. The blood group oligosaccharides, especially the Lewis type, are probably the best example of a relatively rigid conformation exhibiting primarily internal motion of the first kind (4-9).In addition to this first kind of motion, more flexible oligosaccharides can also present a second kind of internal motion which is characterized by larger excursions of glycosidic dihedral angles crossing high-energy barriers from one well-defined minimum to another. The existence of this second kind of flexibility may be inferred when the experimental data are not compatible with a single conformation. The time scale of such motions depends on the height of the barrier separating the energy minima and could range from nanoseconds to microseconds. At this point, we have available limited information, either experimental or theoretical, regarding the ki...

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Two-bond 13C-13C spin-coupling constants in carbohydrates: effect of structure on coupling magnitude and sign

Cited by 54 publications

References 26 publications

Verification of the Projection Resultant Method for Two-Bond13C–13C Coupling Sign Determinations in Carbohydrates

Verification of the Projection Resultant Method for Two-Bond13C–13C Coupling Sign Determinations in Carbohydrates

Conformational Analysis in Solution by NMR

New Strategy for the Conformational Analysis of Carbohydrates Based on NOE and ¹³C NMR Coupling Constants. Application to the Flexible Polysaccharide of Streptococcus mitis J22

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Two-bond 13C-13C spin-coupling constants in carbohydrates: effect of structure on coupling magnitude and sign

Cited by 54 publications

References 26 publications

Verification of the Projection Resultant Method for Two-Bond13C–13C Coupling Sign Determinations in Carbohydrates

Verification of the Projection Resultant Method for Two-Bond13C–13C Coupling Sign Determinations in Carbohydrates

Conformational Analysis in Solution by NMR

New Strategy for the Conformational Analysis of Carbohydrates Based on NOE and 13C NMR Coupling Constants. Application to the Flexible Polysaccharide of Streptococcus mitis J22

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Product

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New Strategy for the Conformational Analysis of Carbohydrates Based on NOE and ¹³C NMR Coupling Constants. Application to the Flexible Polysaccharide of Streptococcus mitis J22