A structured understanding of cellobiohydrolase I binding to poplar lignin fractions after dilute acid pretreatment

Table 1 Signal assignment and relative intensities of lignin fractions from natural poplar variants in FT-IR spectra

No.	Assignment	Wavenumber (cm⁻¹)	H ₁	H ₂	H ₃	L ₁	L ₂	L ₃
1	Hydroxyl group	3410	0.49	0.68	0.75	0.57	0.73	0.73
2	C–H stretching	2938	0.47	0.67	0.64	0.65	0.89	0.85
3	C=O in unconjugated ketone	1738	0.13	0.54	0.69	1.29	2.36	2.25
4	Aromatic ring	1596	0.83	0.98	1.00	0.86	0.93	0.95
5	Aromatic ring	1513	1.00	1.00	1.00	1.00	1.00	1.00
6	C–H deformation	1459	1.14	1.27	1.27	1.24	1.37	1.36
7	Aromatic ring	1424	0.95	1.06	1.10	1.10	1.34	1.35
8	Syringyl and condensed guaiacyl	1324	1.01	1.06	1.06	1.05	1.06	1.08
9	C–O stretching	1215	1.39	1.66	1.66	1.85	2.41	2.37
10	Aromatic C–H deformation in syringyl	1112	1.89	1.96	2.00	1.85	1.76	1.78
11	C–O–C stretching	1030	0.91	1.29	1.39	1.01	1.14	1.10

The relative intensity was calculated as the ratio of the intensity of the band to the intensity of band at 1513 cm⁻¹

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