Wageningen University, Laboratory of Food Chemistry, PO Box 8129, 6700 EV Wageningen, The Netherlands.
Carbohydr Polym. 2013 Sep 12;97(2):368-75. doi: 10.1016/j.carbpol.2013.05.045. Epub 2013 May 25.
Differently modified xanthans, varying in degree of acetylation and/or pyruvylation were incubated with the experimental cellulase mixture C1-G1 from Myceliophthora thermophila C1. The ionic strength and/or temperature of the xanthan solutions were varied, to obtain different xanthan conformations. The exact conformation at the selected incubation conditions was determined by circular dichroism. The xanthan degradation was analyzed by size exclusion chromatography. It was shown that at a fixed xanthan conformation, the backbone degradation by cellulases is equal for each type of xanthan. Complete backbone degradation is only obtained at a fully disordered conformation, indicating that only the secondary xanthan structure influences the final degree of hydrolysis by cellulases. It is thereby shown that, independently on the degree of substitution, xanthan can be completely hydrolyzed to oligosaccharides. These oligosaccharides can be used to further investigate the primary structure of different xanthans and to correlate the molecular structure to the xanthan functionalities.
不同修饰的黄原胶，其乙酰化和/或丙酮酸化程度不同，与嗜热真菌 C1 的实验纤维素酶混合物 C1-G1 一起孵育。改变黄原胶溶液的离子强度和/或温度，以获得不同的黄原胶构象。通过圆二色性确定所选孵育条件下的确切构象。通过凝胶渗透色谱法分析黄原胶的降解。结果表明，在固定的黄原胶构象下，每种黄原胶的纤维素酶对主链的降解是相等的。只有在完全无序的构象下才能获得完全的主链降解，这表明只有黄原胶的二级结构影响纤维素酶最终的水解程度。因此，无论取代度如何，黄原胶都可以完全水解为低聚糖。这些低聚糖可用于进一步研究不同黄原胶的一级结构，并将分子结构与黄原胶的功能相关联。
