Molecular directionality in polysaccharide synthesis by glucosyltransferase

我们开发了一种通过还原胺化来标记多糖链还原末端的配方，用于显微镜下的透射电子显微镜观察。该方法被应用于以下方面的研究：1.天然微纤维的结构及其合成的方向性。纤维素和甲壳素多晶型的链状堆积3。酶降解的分子方向性。在某些纤维二糖水解酶的结合模块中具有选择性。纤维素I和β-甲壳素均为“平行向上”结构。这些链的聚合发生在非还原末端。纤维素III是平行的，而II是反平行的，这与以往对这些多态的研究很好地一致。然而，α-甲壳素的还原末端标记与反平行结构不太相符。沙雷氏菌的几丁质酶A和B分别从其还原端和非还原端消化b-甲壳素微纤维。一些纤维生物水解酶的结合模块显示出对纤维素疏水表面的优先吸附：即纤维素晶体的(100)表面。

We have developed a recipe for labeling reducing end of polysaccharide chains by reductive amination for microscopic visualization by TEM. This method was applied to investigate the following topics,1. Structure of native microfibrils and their directionality of synthesis.2. Chain packing in cellulose and chitin polymorphs3. Molecular directionality of enzymatic degradation4. Preference in binding modules of some cellobiohydrolases.1. The "parallel-up" structure was confirmed both for cellulose I and β-chitin. The polymerization of those chains was found to occur at non-reducing ends.2. Cellulose III was parallel while II was anti-parallel, which are in good accord with the previous studies on these polymorphs. However, the reducing end labeling of α-chitin was not in good accord with anti-parallel structure.3. Chitinase A and B from Serratia was found to digest b-chitin microfibrils from their reducing ends and non-reducing ends, respectively.4. Binding modules from some cellobiohydrolases showed preferential adsorption to the hydrophobic surface of cellulose : i.e. (100) surface of cellulose crystals.