Laboratory of Biomass Conversion, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
Phytochem Anal. 2012 May-Jun;23(3):248-53. doi: 10.1002/pca.1350. Epub 2011 Sep 7.
Lignin is the second most abundant biopolymer next to cellulose. However, because of the complexity of the heterogeneous macromolecules, it is difficult to elucidate the polymeric structures of lignin by conventional analytical methods.
To obtain the detailed structures of lignin, we comparatively applied nano-assisted laser desorption/ionisation time-of-flight mass spectrometry (NALDI-TOF MS) and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS).
Synthetic lignin from coniferyl alcohol and an isolated lignin from Pinus densiflora were subjected to NALDI- and MALDI-TOF MS.
We first obtained NALDI-TOF MS of synthetic and isolated lignin. Mass increments of 178 and 196 Da were observed in NALDI- and MALDI-TOF mass spectra of the synthetic and isolated lignin. The mass intervals indicated that radical coupling forming β-O-4 bonds is the major pathway. Peaks in the low molecular mass region between m/z 500 and 800 were observed more extensively using NALDI-TOF MS than MALDI-TOF MS, which enabled detailed analysis of the interunit linkages in lignin.
Owing to the ionisation profile differentiation from MALDI-TOF MS, NALDI-TOF MS is useful for the structural analysis of lignin.
木质素是仅次于纤维素的第二丰富的生物聚合物。然而，由于其复杂的多相大分子结构，传统的分析方法很难阐明木质素的聚合结构。
为了获得木质素的详细结构，我们比较应用了纳米辅助激光解吸/电离飞行时间质谱（NALDI-TOF MS）和基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）。
用松柏醇合成的木质素和从赤松中分离出的木质素进行 NALDI-和 MALDI-TOF MS 分析。
我们首先获得了合成木质素和分离木质素的 NALDI-TOF MS。在合成木质素和分离木质素的 NALDI-和 MALDI-TOF 质谱中观察到 178 和 196 Da 的质量增量。这些质量间隔表明，形成 β-O-4 键的自由基偶联是主要途径。与 MALDI-TOF MS 相比，NALDI-TOF MS 在 m/z 500 到 800 之间的低分子量区域观察到更多的峰，这使得木质素中单元间连接的详细分析成为可能。
由于 NALDI-TOF MS 的离子化谱图与 MALDI-TOF MS 不同，因此 NALDI-TOF MS 可用于木质素的结构分析。
