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Table 3 Quantification of aromatic moieties (lignin, hydroxycinnamates, inter-unit bondages) by combination analysis of 13 C and HSQC NMR spectra of wheat straw isolated CEL

From: Effects of lignin modification on wheat straw cell wall deconstruction by Phanerochaete chrysosporium

Aromatic moieties σ CH(ppm) and assignments Control CEL Two weeks CEL Four weeks CEL Six weeks CEL Eight weeks CEL
Lignin aromatic units       
Syringyl (S) 103.9/6.7 (S2/6), 27.3 20.5 19.4 21.3 24.5
106.4/7.4 (S'2/6 with α oxidization)
Guaiacyl (G) 110.8/6.97 (G2) 39.3 40.8 37.2 40.9 39.8
115.0/6.94 (G5),118.9/6.81 (G6)
p-hydroxyphenyl (H) 127.7/7.21 (H2/6) 1.4 2.2 2.4 2.3 1.8
S/G ratio   0.69 0.50 0.52 0.52 0.61
Hydroxycinnamates       
p-benzonate (PB) 132.4/7.63 (PB2/6) 1.2 ND ND ND 0.2
p-coumarate (pCA) 130.0/7.47 (pCA2/6),115.5/6.79 (pCA3/5) 5.5 2.5 2.7 3.3 3.1
Ferulate (FA) 110.9/7.32 (FA2), 122.5/7.15 (FA6) 6.4 3.9 4.6 5.4 4.5
p-coumarate/ferulate   0.86 0.65 0.58 0.60 0.68
Cinnamates/lignin and tricin   0.18 0.09 0.10 0.12 0.11
Lignan       
Tricin (T) 104.04/7.30 (T 2′/6'), 104.65/7.03 (T3) 5.6 10 12 9.0 6.6
94.1/6.56 (T8), 98.8/6.22 (T6)
Inter-unit bondages       
α-OH/β-O-4 71.1/4.74 (Aα-G), 71.8/4.8 (Aα-S) 33.8 33.9 28.1 33.9 36.5
α-keto/β-O-4 82.7/5.1 (Aα-keto) 2.4 0.8 0.6 0.8 1.1
Total β-O-4   36.5 34.7 28.7 34.7 37.6
Phenylcoumaran (β-5) 85.9/5.5 (Bα), 53.0/3.4 (Bβ) 5.7 4.2 3.3 5.2 4.2
Pino/resinol (β-β') 84.8/4.7 (Cα), 53.5/3.1 (Cβ), 0.9 1.2 1.6 1.5 1.2
Dibenzodioxocin (D) 83.4/4.9 (Dα), 85.5/3.8 (Dβ) 2.0 3.8 2.7 4.0 2.5
Spirodienone (SD) 81.4/5.0 (SDα), 59.5/2.8 (SDβ) ND ND ND ND ND
α,β-diaryl ether (F) 79.6/5.5 (Fα) 2.1 ND ND ND 1.3
γ-ending groups       
γ-OH in X1 structure 62-58/3.8-3.0 1.5 0.9 0.8 1.0 0.9
Acylation on γ position 60.8-58.8/3.8-3.35 15.6 11.1 13.1 11.8 10.1