Laboratory of Sustainable and Catalytic Processing, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
U.S. Department of Energy (DOE) Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, WI 53726, USA.
Angew Chem Int Ed Engl. 2024 Jul 29;63(31):e202404442. doi: 10.1002/anie.202404442. Epub 2024 Jun 24.
Our ability to study and valorize the lignin fraction of biomass is hampered by the fundamental and still unmet challenge of precisely quantifying native lignin's structural features. Here, we developed a rapid elevated-temperature H-C Heteronuclear Single-Quantum Coherence Zero (HSQC) NMR method that enables this precise quantification of native lignin structural characteristics even with whole plant cell wall (WPCW) NMR spectroscopy, overcoming fast spin relaxation in the gel phase. We also formulated a Gaussian fitting algorithm to perform automatic and reliable spectral integration. By combining HSQC measurements with yield measurements following depolymerisation, we can confirm the combinatorial nature of radical coupling reactions during biosynthesis leading to a random sequential organization of linkages within a largely linear lignin chain. Such analyses illustrate how this analytical method can greatly facilitate the study of native lignin structure, which can then be used for fundamental studies or to understand lignin depolymerization methods like reductive catalytic fractionation or aldehyde-assisted fractionation.
我们对生物质中木质素部分进行研究和利用的能力受到一个基本且尚未解决的挑战的阻碍，即精确量化天然木质素结构特征。在这里，我们开发了一种快速高温 H-C 异核单量子相干零（HSQC）NMR 方法，即使使用整个植物细胞壁（WPCW）NMR 光谱也能实现这种精确量化天然木质素结构特征，克服了凝胶相中快速自旋弛豫。我们还制定了高斯拟合算法来进行自动和可靠的光谱积分。通过将 HSQC 测量与解聚后的产率测量相结合，我们可以确认生物合成过程中自由基偶联反应的组合性质，从而导致在主要线性木质素链内的键的随机顺序组织。这些分析说明了这种分析方法如何极大地促进了对天然木质素结构的研究，这可以用于基础研究或理解木质素解聚方法，如还原催化分级或醛辅助分级。
