Table 1. Measurement of the population of conformers for IdoA2S and IdoA residues in hexasaccharides.
| Hexasaccharides | Measured 3JH-H couplings (Hz) (Calculated 3JH-H couplings) |
Population of conformersd |
Sum of square differencee | NOE signals for measuring 2SO conformer population | |||||
|---|---|---|---|---|---|---|---|---|---|
| 3JH1-H2 | 3JH2-H3 | 3JH3-H4 | 3JH4-H5 | 1C4 a | 2SOb | 4C1 c | H2-H5/H4-H5f | ||
| 1-IdoA2S | 2.2 (2.7) | 4.3 (4.1) | 3.2 (3.0) | 2.2 (2.1) | 68% | 32% | – | 0.34 | 0.19 |
| 2-IdoA2S | 2.2 (2.7) | 4.3 (4.1) | 3.2 (3.0) | 2.3 (2.2) | 68% | 32% | – | 0.34 | 0.21 |
| 3-IdoA2S | 3.0 (3.6) | 5.8 (5.5) | 3.6 (3.6) | 2.7 (2.5) | 47% | 53% | – | 0.49 | 0.26 |
| 4-IdoA2S | 3.7 (4.5) | 7.4 (6.9) | 4.0 (4.2) | 3.1 (2.8) | 25% | 75% | – | 1.02 | 0.34 |
| 5-IdoA | 3.0 (3.3) | 5.2 (5.1) | 3.5 (3.4) | 2.7 (2.4) | 53% | 47% | – | 0.20 | 0.34 |
| 6-IdoA | 3.1 (3.4) | 5.3 (5.2) | 3.5 (3.5) | 2.7 (2.4) | 51% | 49% | – | 0.19 | 0.35 |
| 7-IdoA | 2.3 (2.8) | 4.3 (4.1) | 3.4 (3.2) | 2.4 (2.2) | 68% | 29% | 3% | 0.37 | 0.22 |
| 8-IdoA | 2.3 (2.7) | 3.9 (3.8) | 3.5 (3.2) | 2.2 (2.2) | 73% | 19% | 8% | 0.26 | 0.19 |
aCalculated 3JH-H values using Amber 14 with GLYCAM06 parameter39 for 1C4 conformer are 1.35 (3JH1-H2), 2.04 (3JH2-H3), 2.19 (3JH3-H4) and 1.69 Hz (3JH4-H5), respectively.
bCalculated 3JH-H values using Amber 14 with GLYCAM06 parameter39 for 2SO conformer are 5.55 (3JH1-H2), 8.48 (3JH2-H3), 4.82 (3JH3-H4) and 3.14 Hz (3JH4-H5), respectively.
cCalculated 3JH-H values using Amber 14 with GLYCAM06 parameter39 for 4C1 conformer are 7.85 (3JH1-H2), 8.03 (3JH2-H3), 8.5 (3JH3-H4) and 5.08 Hz (3JH4-H5), respectively.
dObtained by least sum of square difference analysis of the calculated and experimental values.
eThe residual sum of squares (RSS) was used to determine how well the calculated population ratios fit the experimental data42.
fThe calculated ratio of NOE H2-H5 signal and H4-H5 signal for pure 2SO, 1C4 and 4C1 conformer is 0.53, 0.05, and 0.03 respectively39.