Molecular directionality in polysaccharide synthesis by glucosyltransferase

我们开发了一种通过还原胺化标记多糖链还原端的方法，用于TEM显微镜下的可视化。该方法应用于以下主题的调查：1。天然微原纤维的结构及其合成方向性纤维素和几丁质多态中的链式包装。酶降解的分子方向性一些纤维素生物水解酶结合模块的偏好。证实了纤维素I和β-几丁质的“平行”结构。这些链的聚合被发现发生在非还原端。纤维素III是平行的，而纤维素II是反平行的，这与以往对这些多态性的研究结果一致。但α-几丁质的还原端标记与反平行结构不太符合。发现来自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 -几丁质微原纤维。一些纤维素生物水解酶的结合模在纤维素的疏水表面，即纤维素晶体的（100）表面表现出优先吸附。

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.