Horikawa Yoshiki, Sugiyama Junji
Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto 611-0011, Japan.
Biomacromolecules. 2009 Aug 10;10(8):2235-9. doi: 10.1021/bm900413k.
We report an FTIR spectroscopic technique combined with intracrystalline deuteration and rehydrogenation of cellulose samples to investigate the localization of I(alpha) and I(beta) domains within a cellulose microfibril obtained from I(alpha)-rich algae. When Glaucocystis cellulose incompletely converted from I(alpha) to I(beta) was deuterated and rehydrogenated at elevated temperature, OD groups involved in hydrogen bonding in the I(beta) domain first reverted to OH, followed by those in the I(alpha) domain, suggesting that the I(alpha) core domain was surrounded by the I(beta) domain in an artificially induced sample. We concluded that this I(alpha) --> I(beta) conversion proceeded from the surface toward the core. Native celluloses from Valonia and Cladophora were first deuterated without changing the allomorphic composition, and rehydrogenation was studied from I(alpha)- and I(beta)-specific absorbances. Surprisingly, both absorbances changed synchronously, clearly indicating that the simple "skin-core" distribution model of I(alpha) and I(beta) domains is not realistic at least for these native celluloses.
我们报道了一种傅里叶变换红外光谱技术，该技术结合了纤维素样品的晶体内氘化和再氢化，以研究从富含I(α)的藻类中获得的纤维素微纤丝内I(α)和I(β)结构域的定位。当不完全从I(α)转化为I(β)的蓝隐藻纤维素在高温下进行氘化和再氢化时，I(β)结构域中参与氢键形成的OD基团首先恢复为OH，随后是I(α)结构域中的基团，这表明在人工诱导的样品中I(α)核心结构域被I(β)结构域包围。我们得出结论，这种I(α)→I(β)的转变是从表面向核心进行的。首先对来自伞藻属和刚毛藻属的天然纤维素进行氘化，而不改变其同质多晶组成，并根据I(α)和I(β)特异性吸光度研究再氢化过程。令人惊讶的是，两种吸光度同步变化，这清楚地表明，至少对于这些天然纤维素来说，I(α)和I(β)结构域简单的“皮-核”分布模型是不现实的。
