Cell wall localized heterogeneous polyesters are widespread in land plants. The composition of these polyesters, such as cutin, suberin, or more plant‐specific forms such as the flax seed coat lignan macromolecule, can be determined after total hydrolysis of the ester linkages. The main bottleneck in the structural characterization of these macromolecules, however, resides in the determination of the higher order monomer sequences. Partial hydrolysates of the polyesters release a complex mixture of fragments of different lengths, each present in low abundance and therefore are challenging to structurally characterize. Here, a method is presented by which liquid chromatography–mass spectrometry (LC‐MS) profiles of such partial hydrolysates are searched for pairs of related fragments. LC‐MS peaks that show a mass difference corresponding to the addition of one or more macromolecule monomers were connected in a network. Starting from the lowest molecular weight peaks in the network, the annotation of the connections as the addition of one or more polyester monomers allows the prediction of consecutive and increasingly complex adjacent peaks. Multi‐stage MS (MSn) experiments further helped to reject, corroborate, and sometimes refine the structures predicted by the network. As a proof of concept, this procedure was applied to partial hydrolysates of the flax seed coat lignan macromolecule, and allowed to characterize 120 distinct oligo‐esters, consisting of up to six monomers, and containing monomers and linkages for which incorporation in the lignan macromolecule had not been described before. These results showed the capacity of the approach to advance the structural elucidation of complex plant polyesters.

中文翻译：

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基于目标的液相色谱-质谱联用的工作流程，用于植物聚酯的结构表征。

细胞壁局部异质聚酯广泛存在于陆地植物中。这些聚酯的组成，例如角质，木栓质或更植物特有的形式，例如亚麻籽皮木脂素大分子，可以在酯键完全水解后确定。然而，这些大分子的结构表征的主要瓶颈在于确定高阶单体序列。聚酯的部分水解产物释放出不同长度的片段的复杂混合物，每个片段的丰度都较低，因此在结构表征方面存在挑战。在这里，提出了一种方法，通过该方法可以搜索此类部分水解产物的液相色谱-质谱（LC-MS）谱图，以找到相关片段对。在网络中连接了LC-MS峰，这些峰显示出与添加一种或多种大分子单体相对应的质量差异。从网络中最低的分子量峰开始，通过添加一种或多种聚酯单体来注释连接，可以预测连续且日益复杂的相邻峰。多阶段MS（MSn）实验进一步帮助拒绝，证实和有时完善了网络预测的结构。作为概念的证明，此程序适用于亚麻籽皮木脂素大分子的部分水解产物，并允许表征120种不同的低聚酯，其中最多包含6个单体，并包含掺入木脂素大分子中的单体和键之前没有描述过。