Table 2. Summary of NMR and Mass Spectrometry Evidence for Structural Units in APAP1, All of Which Is Consistent with the Proposed APAP1 Structure Shown in Figure 4.
| Structure Unit | Identified Structures | Techniques Used |
|---|---|---|
| 1 AG-to-Hyp linkage | Hyp-O-Galp | TOCSY and HSQC spectra of YS1-HP2627 and YS2-HP3132 |
| Hyp-O-AG | TOCSY and HSQC spectra of YS1-HP2627 and YS2-HP3132 | |
| 2 Type II AG | -β-d-Galpbb-1→3-β-d-Galpbb-1- | HMBC spectrum of YS2 and NOESY spectrum of YS1 HP-2627 |
| -β-d-Galpbb-1→6-β-d-Galpbb-1- | NOESY spectrum of YS1-HP2627 | |
| -β-d-Galpsc-1→6-β-d-Galpbb-1- | NOESY spectrum of YS1-HP2627 | |
| 3 GlcA side chain of AG | -β-d-GlcAp-1→6-β-d-Galpsc-1- | NOESY spectra of YS1-HP2627 and YS2-HP2627 |
| 4 Pectin to AG GlcA linkage | α-d-GalAp-1→-2-α-L-Rhap-1→4-β-d-GlcAp | HMQC spectrum of YS1-HP2627 |
| 5 RG-I linkage | −2-α-l-Rhap-1→4-α-d-GalAp-1- | HMBC spectrum of YS2 |
| 6 HG-RG-I attachment | Rha-GalA-Rha-GalA-(GalA)4-GalA-(OAc)-OH | CID-MS/MS of RGH released oligomers from YS2 |
| Rha-GalA-Rha-GalA-(GalA)3-GalAOH | CID-MS/MS of RGH released oligomers from YS2 | |
| 7 Different linkages of Xyls in arabinoxylan | −4[α-l-Araf-1→2,AcO-3]-β-d-Xylp-1→4-β-d-Xylp-1- | HMBC spectrum of YS2 |
| −4[AcO-3]-β-d-Xylp-1→4-β-d-Xylp-1- | HMBC spectrum of YS2 | |
| −4-β-d-Xylp-1→4-β-d-Xylp-1- | HMBC spectrum of YS2 | |
| Xylp6, Xylp5, Xylp4 | CID-MS/MS of RGH released oligomers from YS2 | |
| 8 Arabinose to Xyl linkage in arabinoxylan | α-l-Araf-1→2-β-d-Xylp- | HMBC spectrum of YS2 and NOESY spectrum of YS2-HP2627 |
| 9 Arabinoxylan to AG arabinosyl side chain linkage | β-Xylp-1→5-α-l-Araf | HMBC spectrum of YS2 and NOESY spectrum of YS1-HP2627 |
| 10 Arabinoxylan to RG-I rhamnosyl residue linkage | β-Xylp-1→4-α-l-Rhap | NOESY spectrum of YS2-HP2627 |
| Xylp-(Xylp)3-Xylp-(AcO)Rha-GalA-Rha-GalA | CID-MS/MS of RGH released oligomers from YS2 | |
| Xylp-(Xylp)2-Xylp-(AcO)Rha-GalA-Rha-GalA | CID-MS/MS of RGH released oligomers from YS2 | |
| 11 β-1,4-Galactan side chain of RG-I | →4-β-d-Galp-1→4-α-(2-)-Rhap | NOESY spectrum of YS2-HP2627 |
Galbb represents Gal residues in the β-1→3-galactan backbone of the AG domain. Galsc represents side chain β-Gal residues connected 1→6 to the β-1→3-galactan backbone. Structural unit numbers listed in this table are the same as those marked in Figure 4. YS1-HP2627, YS2-HP2627, and YS2-HP3132 represent the Hyp-O-polysaccharide fractions 26 plus 27, and 31 plus 32, generated from YS1 and YS2, respectively. HMBC is heteronuclear multiple-bond correlation spectroscopy.