BioEnergy Science Center, School of Chemistry and Biochemistry, Institute of Paper Science and Technology, Georgia Institute of Technology, 500 10th Street, Atlanta, Georgia 30332, USA.
J Agric Food Chem. 2012 Feb 15;60(6):1419-27. doi: 10.1021/jf204853b. Epub 2012 Feb 1.
The average spatial dimensions between major biopolymers within the plant cell wall can be resolved using a solid-state NMR technique referred to as a (13)C cross-polarization (CP) SELDOM (selectively by destruction of magnetization) with a mixing time delay for spin diffusion. Selective excitation of specific aromatic lignin carbons indicates that lignin is in close proximity to hemicellulose followed by amorphous and finally crystalline cellulose. (13)C spin diffusion time constants (T(SD)) were extracted using a two-site spin diffusion theory developed for (13)C nuclei under magic angle spinning (MAS) conditions. These time constants were then used to calculate an average lower-limit spin diffusion length between chemical groups within the plant cell wall. The results on untreated (13)C enriched corn stover stem reveal that the lignin carbons are, on average, located at distances ∼0.7-2.0 nm from the carbons in hemicellulose and cellulose, whereas the pretreated material had larger separations.
利用一种称为（13）C 交叉极化（CP）的固态 NMR 技术，可以分辨植物细胞壁中主要生物聚合物之间的平均空间维度，该技术具有自旋扩散的混合时间延迟（SELDOM）。特定芳族木质素碳的选择性激发表明木质素与半纤维素紧密相邻，然后是非晶态，最后是结晶纤维素。使用针对 MAS 条件下（13）C 核开发的双位点自旋扩散理论，提取（13）C 自旋扩散时间常数（T（SD））。然后，使用这些时间常数来计算植物细胞壁内化学基团之间的平均下限自旋扩散长度。对未经处理的（13）C 富集玉米秸秆的研究结果表明，木质素碳的平均位置距离半纤维素和纤维素中的碳约为 0.7-2.0nm，而预处理材料的分离度更大。
