Table 5.
Experimentala and calculated values of transglycosidic 3J (Hz) coupling constants (Fig. 3) for middle unitsb of linear oligoglucosamines 1a–6b.
| Method | Non-N-acetylated oligoglucosamines | N-acetylated oligoglucosamines | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| # | Jφ | JψR | JψS | JωS | JωS | # | Jφ | JψR | JψS | JωR | JωS | |
| experiment | 1a | 3.0 | 2.9 | 3.0 | 5.0 | 2.0g | 1b | 4.2 | 2.8 | 3.1 | 6.1 | 1.9g |
| calc.c(ε = 81) | 3.4 | 2.3 | 2.3 | 8.5 | 3.1 | 3.3 | 2.2 | 2.0 | 2.3 | 1.9 | ||
| calc.d(SASA) | 3,6 | 1,8 | 2,1 | 9,4 | 1,6 | 3.7 | 2.7 | 2.3 | 6.8 | 1.7 | ||
| calc.e (NH3) | 3.4 | 2.3 | 2.3 | 6.6 | 2.2 | |||||||
| experiment | 2a | 3.5 | 3.0 | 2.3 | -f | 2.0g | 2b | 4.3 | 3.0 | 2.9 | -f | 2.1g |
| calc. (ε = 81) | 3.3 | 2.3 | 2.3 | 6.7 | 2.4 | 3.4 | 2.4 | 2.1 | 6.4 | 3.5 | ||
| calc. (SASA) | 3,7 | 2,1 | 2,1 | 9,4 | 1,8 | 3.1 | 2.3 | 2.1 | 3.6 | 2.2 | ||
| calc. (NH3) | 3.4 | 2.0 | 2.3 | 5.4 | 2.3 | |||||||
| experiment | 3a | 3.8 | 2.9 | 2.8 | -f | 2.0g | 3b | 4.2 | 2.7 | 2.6 | -f | 2.0g |
| calc. (ε = 81) | 3.3 | 2.4 | 2.6 | 5.5 | 2.0 | 3.5 | 3.1 | 2.9 | 7.9 | 1.9 | ||
| calc. (SASA) | 3,9 | 2,0 | 2,3 | 8,4 | 3,0 | 3.1 | 2.5 | 2.0 | 4.8 | 1.7 | ||
| calc. (NH3) | 3.3 | 2.4 | 2.5 | 6.2 | 2.0 | |||||||
| experiment | 4a | -f | -f | -f | -f | -f | 4b | ≈3.8h | ≈2.9h | ≈2.7h | -f | 2.0g |
| calc. (ε = 81) | 3.2 | 2.8 | 2.4 | 5.8 | 2.1 | 3.4 | 2.6 | 2.4 | 4.4 | 2.2 | ||
| calc. (SASA) | 3,5 | 2,2 | 2,1 | 6,1 | 2,7 | 3.1 | 2.7 | 1.9 | 7.2 | 1.8 | ||
| calc. (NH3) | 3.3 | 2.6 | 2.3 | 5.0 | 2.0 | |||||||
| experiment | 5a | -j | -j | -j | -j | -j | 5b | -j | -j | -j | -j | -j |
| calc. (ε = 81) | 3.3 | 2.9 | 2.6 | 6.3 | 2.7 | 3.3 | 2.5 | 2.2 | 3.7 | 2.0 | ||
| calc. (SASA) | 3,5 | 2,3 | 2,0 | 6,1 | 2,5 | 3.3 | 2.7 | 2.1 | 7.7 | 1.8 | ||
| calc. (NH3) | 3.2 | 2.1 | 2.4 | 4.1 | 3.5 | |||||||
| experiment | 6a | -f | -f | -f | -f | -f | 6b | -f | -f | -f | -f | -f |
| calc. (ε = 81) | 3.4 | 2.7 | 2.7 | 4.4 | 2.1 | 3.4 | 3.2 | 2.8 | 6.4 | 2.7 | ||
| calc. (SASA) | 3,7 | 2,2 | 2,1 | 7,0 | 2,5 | 3.2 | 2.6 | 1.8 | 5.3 | 2.1 | ||
| calc. (NH3) | 3.2 | 2.4 | 2.4 | 6.8 | 2.2 | |||||||
The NMR spectra were acquired at the temperature of 300–307 K. For each compound the temperature was chosen so that to exclude the overlap of the solvent signal (HOD) with signals of the anomeric protons in 1H NMR spectrum.
The data for all disaccharide units of oligoglucosamines are presented in Supplementary Materials.
The values of constants calculated for solvation model ε = 81 at TE = 300K.
The values of constants calculated for SASA implicit solvation model at TE = 300K.
The values of constants calculated for NH3-model of free oligoglucosamines 1a–6a at ε = 81 and TE = 300K.
Not determined due to the peak overlaps.
The value of constant was obtained by the curve-fitting algorithm25 which was applied for analysis of multiplet due to the small value of the interesting constant and the broad lines in multiplet.
The value of the coupling constant could not be measured exactly because the peaks overlap in the spectra.
Not measured.