Corzana Francisco, Motawia Mohammed S, Hervé du Penhoat Catherine, van den Berg Frans, Blennow Andreas, Perez Serge, Engelsen Søren B
Contribution from the Centre for Advanced Food Studies (LMC), The Royal Veterinary and Agricultural University (KVL), Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
J Am Chem Soc. 2004 Oct 13;126(40):13144-55. doi: 10.1021/ja048622y.
The hydration behavior of a model compound for the amylopectin branch point, methyl 6'-alpha-maltosyl-alpha-maltotrioside, was investigated by combining molecular dynamics simulations in explicit water, 500 MHz NMR spectroscopy, including pulsed field gradient diffusion measurements, and exploratory multivariate data analysis. In comparison with results on a tetrasaccharide analogue, the study reveals that the conformational diversity of the three-bond alpha-(1-->6) linkage becomes quite limited in aqueous solution upon the addition of a fifth glucose residue that elongates the alpha-(1-->6) branch. This investigation reveals two plausible starch branch point structures, one that permits the formation of double helices and one that is adapted for interconnection of double helices. The apparent rigidity of the former is explained by the presence of water pockets/bridges in the vicinity of the branch point that lock the pentasaccharide structure into one conformational family that is able to accommodate the creation of the double-helical amylopectin structure.
通过结合在显式水中的分子动力学模拟、500兆赫核磁共振光谱（包括脉冲场梯度扩散测量）以及探索性多变量数据分析，对支链淀粉分支点的模型化合物6'-α-麦芽基-α-麦芽三糖苷进行了水合行为研究。与四糖类似物的结果相比，该研究表明，在添加延长α-(1→6)分支的第五个葡萄糖残基后，三键α-(1→6)连接的构象多样性在水溶液中变得相当有限。这项研究揭示了两种可能的淀粉分支点结构，一种允许形成双螺旋，另一种适合双螺旋的相互连接。前者明显的刚性是由分支点附近存在的水袋/水桥所解释的，这些水袋/水桥将五糖结构锁定在一个构象家族中，该构象家族能够适应双螺旋支链淀粉结构的形成。
