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Substituent distribution in carboxymethl glucans: development of a quantitative method for the determination of the substituent distribution along and over the polymer chains

羧甲基葡聚糖中的取代基分布：开发一种定量方法来确定聚合物链上的取代基分布

基本信息

批准号：
236656131
负责人：
Professorin Dr. Petra Mischnick
金额：
--
依托单位：
Institut für Lebensmittelchemie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2015-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/236656131?language=en
关键词：
Substituent distribution carboxymethl glucans development

项目摘要

Polysaccharide derivatives are complex mixtures which beside molecular weight vary with respect to the degree and distribution of substituents. The latter has to be considered on various, related hierarchical structure levels (in the glucosyl unit, along the polysaccharide chain, and over the polysaccharide chains). While for nonionic cellulose ethers powerful methods for the various levels of substitution patterns have been developed and improved, no such methods exist for the anionic carboxymethyl ethers.Carboxymethyl cellulose (CMC) is the most abundant cellulose derivative. The relationship between the properties (e.g. water solubility) of this polyelectrolyte and the substituent distribution are not fully understood, since the latter cannot be described in detail, but is restricted to average values. Carboxymethylation is also applied to other polysaccharides like starch, dextran and hemicelluloses and raises the same questions.Therefore, it is the aim of the project, based on long-year experience in the field of the analysis of substituent patterns of polysaccharide derivatives, to develop a powerful method for the determination of the CM-distribution in carboxymethyl glucans (CMG). To obtain correct patterns of CM groups, representative mixtures of oligomeric sequences must be prepared from the polymer molecules, and for each DP, the substituent profiles must be determined quantitatively.Taking all data into account, the comparison of the oligomer profiles with the random model, and the change of the profiles with DP, shall allow to draw conclusions on heterogeneities (DS gradient, bimodal distributions). Based on the preliminary work, an LC-MS method shall be worked out. Essential is an appropriate sample preparation and control of all steps with respect to discriminating effects. Concretely, the following milestones shall be investigated and worked out: disintegration of the material, kinetic studies of partial depolymerization and control of randomness, derivatisation- and labeling strategies, development of separation and mass spectrometric methods (LC-ESI-MS, MALDI-ToF-MS), quantitative evaluation and model calculations; methods worked out shall be applied to various CMG with the same DS but different properties.Furthermore, a multiple-step depolymerization-labeling strategy shall allow to differentiate heterogeneities of second and first order.

多糖衍生物是复杂的混合物，除了分子量之外，还随取代基的程度和分布而变化。后者必须在各种相关的层次结构水平上考虑（在葡萄糖基单元中，沿着多糖链，以及在多糖链上）。虽然对于非离子纤维素醚，已经开发和改进了用于各种水平取代模式的有效方法，但对于阴离子羧甲基醚，不存在这样的方法。羧甲基纤维素（CMC）是最丰富的纤维素衍生物。这种聚电解质的性质（例如水溶性）与取代基分布之间的关系尚未完全了解，因为后者无法详细描述，而仅限于平均值。羧甲基化也适用于淀粉、葡聚糖和半纤维素等其他多糖，并引发了相同的问题。因此，该项目的目的是基于多糖衍生物取代基模式分析领域的长期经验，开发一种强大的方法来测定羧甲基葡聚糖（CMG）中的CM分布。为了获得正确的 CM 基团模式，必须从聚合物分子中制备具有代表性的低聚序列混合物，并且对于每个 DP，必须定量确定取代基分布。考虑到所有数据，低聚物分布与随机模型的比较以及分布随 DP 的变化，应能够得出异质性（DS 梯度、双峰分布）的结论。在前期工作的基础上，制定LC-MS方法。重要的是适当的样品制备和对所有步骤的区分效果的控制。具体而言，应研究和制定以下里程碑：材料的崩解、部分解聚的动力学研究和随机性控制、衍生化和标记策略、分离和质谱方法（LC-ESI-MS、MALDI-ToF-MS）的开发、定量评估和模型计算；制定的方法应适用于具有相同DS但不同性质的各种CMG。此外，多步解聚标记策略应允许区分二级和一级异质性。