Table 2.
Major signal assignments in solid-state 13C MAS NMR spectra of rice cell walls.
| Assignment | Resonance (ppm) |
|---|---|
| I′9 (aldehyde lignin C9) | 190 |
| C1 (cellulose C1) | 105 |
| X1a (rigid/twofold xylan C1) | 105a |
| X1b (mobile/threefold xylan C1) | 103a |
| C4a (crystalline/internal cellulose C4) | 89 |
| C4b (amorphous/surface cellulose C4) | 84 |
| X4a (rigid/twofold xylan C4) | 82a |
| X4b (threefold/mobile xylan C4) | 77a |
| X2,3 (xylan C2 and C3) | 75-72a |
| C2,3,5 (cellulose C2, C3 and C5) | 75-72 |
| C6a (crystalline/internal cellulose C6) | 65 |
| X5 (xylan C5) | 64a |
| C6b (amorphous/surface cellulose C6) | 63 |
| OMe (lignin methoxyl CH3) | 57 |
aNot well resolved in this study. Chemical shift values are according to Simmons et al.60.