Department of Biochemistry, and DOE Great Lakes BioEnergy Research Center, University of Wisconsin, Madison, Wisconsin 53706, USA.
Org Biomol Chem. 2010 Feb 7;8(3):576-91. doi: 10.1039/b916070a. Epub 2009 Dec 3.
NMR fingerprinting of the components of finely divided plant cell walls swelled in DMSO has been recently described. Cell wall gels, produced directly in the NMR tube with perdeutero-dimethylsulfoxide, allowed the acquisition of well resolved/dispersed 2D (13)C-(1)H correlated solution-state NMR spectra of the entire array of wall polymers, without the need for component fractionation. That is, without actual solubilization, and without apparent structural modification beyond that inflicted by the ball milling and ultrasonication steps, satisfactorily interpretable spectra can be acquired that reveal compositional and structural details regarding the polysaccharide and lignin components in the wall. Here, the profiling method has been improved by using a mixture of perdeuterated DMSO and pyridine (4 : 1, v/v). Adding pyridine provided not only easier sample handling because of the better mobility compared to the DMSO-d(6)-only system but also considerably elevated intensities and improved resolution of the NMR spectra due to the enhanced swelling of the cell walls. This modification therefore provides a more rapid method for comparative structural evaluation of plant cell walls than is currently available. We examined loblolly pine (Pinus taeda, a gymnosperm), aspen (Populus tremuloides, an angiosperm), kenaf (Hibiscus cannabinus, an herbaceous plant), and corn (Zea mays L., a grass, i.e., from the Poaceae family). In principle, lignin composition (notably, the syringyl : guaiacyl : p-hydroxyphenyl ratio) can be quantified without the need for lignin isolation. Correlations for p-coumarate units in the corn sample are readily seen, and a variety of the ferulate correlations are also well resolved; ferulates are important components responsible for cell wall cross-linking in grasses. Polysaccharide anomeric correlations were tentatively assigned for each plant sample based on standard samples and various literature data. With the new potential for chemometric analysis using the 2D NMR fingerprint, this gel-state method may provide the basis for an attractive approach to providing a secondary screen for selecting biomass lines and for optimizing biomass processing and conversion efficiencies.
最近有人描述了在 DMSO 中膨胀的细植物细胞壁成分的 NMR 指纹图谱。在 NMR 管中直接用氘代二甲亚砜（perdeutero-dimethylsulfoxide）生产的细胞壁凝胶，允许对整个细胞壁聚合物阵列进行良好分辨/分散的二维（13）C-（1）H 相关溶液状态 NMR 谱的采集，而无需进行组分分级。也就是说，无需实际溶解，而且除了球磨和超声步骤所造成的结构修改之外，无需明显的结构修改，就可以获得可满意解释的谱图，从而揭示细胞壁中多糖和木质素成分的组成和结构细节。在这里，通过使用氘代二甲亚砜和吡啶（4：1，v/v）的混合物，对该分析方法进行了改进。与仅用 DMSO-d(6)的系统相比，添加吡啶不仅提供了更好的流动性，从而更便于处理样品，而且还由于细胞壁的溶胀增强，大大提高了 NMR 光谱的强度和分辨率。因此，这种改进为植物细胞壁的比较结构评估提供了一种比当前方法更快的方法。我们检查了火炬松（Pinus taeda，裸子植物）、白杨（Populus tremuloides，被子植物）、麻疯树（Hibiscus cannabinus，草本植物）和玉米（Zea mays L.，禾本科植物）。原则上，无需分离木质素就可以定量木质素组成（尤其是愈创木酚：丁香酚：对羟苯基的比例）。可以轻松看到玉米样品中对香豆酸单元的相关性，并且各种阿魏酸相关性也得到了很好的分辨；阿魏酸是负责禾本科植物细胞壁交联的重要成分。根据标准样品和各种文献数据，我们对每种植物样品的多糖端基相关进行了初步分配。利用二维 NMR 指纹图谱的新的化学计量学分析潜力，这种凝胶状态的方法可能为选择生物质系的二次筛选以及优化生物质加工和转化效率提供一种有吸引力的方法提供了基础。
