Gray-Weale Angus A, Cave Richard A, Gilbert Robert G
School of Chemistry, Monash University, Victoria 3800, Australia.
Biomacromolecules. 2009 Sep 14;10(9):2708-13. doi: 10.1021/bm900761q.
A method for interpreting multiple-detection size separation data of complex branched homopolymers [Konkolewicz, D.; Gilbert, R. G.; Gray-Weale, A. Phys. Rev. Lett. 2007, 98, 238301] is applied to starch. The method, whose application is described in detail, uses the sample's weight and number distributions over polymer sizes, along with the molecular weight distribution of the individual branches (or their average degree of polymerization). The branch-length and number size distributions are used to generate the weight distribution of a hypothetical molecule with the same branch-length and number distributions but where the branches are randomly joined; this reference weight distribution is then compared to the actual one. The method is applied to size-exclusion chromatography (SEC) data for starch from a particular rice variety, the first time such data have been reported for a native starch. Comparison with the randomly branched reference function shows that the amylopectin component is consistent with random branching on the distance scale of this measurement, 10(2)-10(3) nm. This implies that on the size scale commensurate with that of a whole amylopectin chain, branching is pseudorandom, even though there is nonrandom branching on the much smaller scale of individual branches and clusters.
一种用于解释复杂支化均聚物多检测尺寸分离数据的方法[康科莱维茨，D；吉尔伯特，R.G；格雷 - 韦尔，A.《物理评论快报》2007年，98卷，238301期]被应用于淀粉。该方法的应用已详细描述，它使用聚合物尺寸上的样品重量和数量分布，以及各个分支的分子量分布（或其平均聚合度）。支链长度和数量尺寸分布用于生成具有相同支链长度和数量分布但支链随机连接的假设分子的重量分布；然后将该参考重量分布与实际分布进行比较。该方法应用于来自特定水稻品种淀粉的尺寸排阻色谱（SEC）数据，这是首次报道天然淀粉的此类数据。与随机支化参考函数的比较表明，在该测量的距离尺度（10² - 10³纳米）上，支链淀粉成分与随机支化一致。这意味着在与整个支链淀粉链相当的尺寸尺度上，分支是准随机的，尽管在单个分支和簇的小得多的尺度上存在非随机分支。
