Two-bond 13C–13C spin-coupling constants in carbohydrates: New measurements of coupling signs

Zhao, Shikai; Bondo, Gail; Zajíček, Jaroslav; Serianni, Anthony S.

doi:10.1016/s0008-6215(98)00123-2

Cited by 24 publications

(34 citation statements)

References 36 publications

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“…113 These sign determinations provided experimental confirmation of the relative signs of 2 J CCC and 2 J COC predicted by an empirical, projection resultant method. 114,115 …”

Section: Vicinal Coupling Constantsmentioning

confidence: 60%

Chapter 3 Developments in the Karplus Equation as they Relate to the NMR Coupling Constants of Carbohydrates

Coxon

2009

Advances in Carbohydrate Chemistry and Biochemistry

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“…113 These sign determinations provided experimental confirmation of the relative signs of 2 J CCC and 2 J COC predicted by an empirical, projection resultant method. 114,115 …”

Section: Vicinal Coupling Constantsmentioning

confidence: 60%

Chapter 3 Developments in the Karplus Equation as they Relate to the NMR Coupling Constants of Carbohydrates

Coxon

2009

Advances in Carbohydrate Chemistry and Biochemistry

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“… a In Hz ± 0.1 Hz, in 2 H 2 O, 22 °C; an entry of ∼0 denotes J < 0.5 Hz; signs of geminal couplings are shown in parentheses. b Data for 31 (or the corresponding ethyl glycosides) were taken from ref ( J CH ) and ref ( J CC ). c The (+) signs of 2 J CCC values in βXyl p and βMan p rings were determined by analogy to 2 J C1,C3 and 2 J C2,C4 values in methyl β- d -glucopyranoside, both of which have (+) signs based on experimental measurements and/or use of the projection resultant method (ref ). …”

Section: Resultsmentioning

confidence: 99%

“… c The (+) signs of 2 J CCC values in βXyl p and βMan p rings were determined by analogy to 2 J C1,C3 and 2 J C2,C4 values in methyl β- d -glucopyranoside, both of which have (+) signs based on experimental measurements and/or use of the projection resultant method (ref ). …”

Section: Resultsmentioning

confidence: 99%

Synthesis and O-Glycosidic Linkage Conformational Analysis of ¹³C-Labeled Oligosaccharide Fragments of an Antifreeze Glycolipid

et al. 2019

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NMR studies of two 13C-labeled disaccharides and a tetrasaccharide were undertaken that comprise the backbone of a novel thermal hysteresis glycolipid containing a linear glycan sequence of alternating [βXylp-(1→4)-βManp-(1→4)] n dimers. Experimental trans-glycoside NMR J-couplings, parameterized equations obtained from density functional theory (DFT) calculations, and an in-house circular statistics package (MA’AT) were used to derive conformational models of linkage torsion angles ϕ and ψ in solution, which were compared to those obtained from molecular dynamics simulations. Modeling using different probability distribution functions showed that MA’AT models of ϕ in βMan(1→4)βXyl and βXyl(1→4)βMan linkages are very similar in the disaccharide building blocks, whereas MA’AT models of ψ differ. This pattern is conserved in the tetrasaccharide, showing that linkage context does not influence linkage geometry in this linear system. Good agreement was observed between the MA’AT and MD models of ψ with respect to mean values and circular standard deviations. Significant differences were observed for ϕ, indicating that revision of the force-field employed by GLYCAM is probably needed. Incorporation of the experimental models of ϕ and ψ into the backbone of an octasaccharide fragment leads to a helical amphipathic topography that may affect the thermal hysteresis properties of the glycolipid.

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“…C-H bond lengths vary with bond orientation with a systematic trend toward shorter lengths when the bond orientation is quasiequatorial and longer bonds when quasiaxial (42) J C1-O4-C4-C3 . The contribution of the first pathway can be estimated theoretically by using the projection sum method (38), while the contribution of the second pathway can be calculated using eq 3. A final source of information can be obtained by a qualitative analysis of NOE data within the Galf ring d protons.…”

Section: Resultsmentioning

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: New measurements of coupling signs

Cited by 24 publications

References 36 publications

Chapter 3 Developments in the Karplus Equation as they Relate to the NMR Coupling Constants of Carbohydrates

Chapter 3 Developments in the Karplus Equation as they Relate to the NMR Coupling Constants of Carbohydrates

Synthesis and O-Glycosidic Linkage Conformational Analysis of ¹³C-Labeled Oligosaccharide Fragments of an Antifreeze Glycolipid

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: New measurements of coupling signs

Cited by 24 publications

References 36 publications

Chapter 3 Developments in the Karplus Equation as they Relate to the NMR Coupling Constants of Carbohydrates

Chapter 3 Developments in the Karplus Equation as they Relate to the NMR Coupling Constants of Carbohydrates

Synthesis and O-Glycosidic Linkage Conformational Analysis of 13C-Labeled Oligosaccharide Fragments of an Antifreeze Glycolipid

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

Contact Info

Product

Resources

About

Synthesis and O-Glycosidic Linkage Conformational Analysis of ¹³C-Labeled Oligosaccharide Fragments of an Antifreeze Glycolipid

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