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首页> 外文期刊>Journal of mass spectrometry: JMS >Electron transfer dissociation versus collisionally activated dissociation of cationized biodegradable polyesters
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Electron transfer dissociation versus collisionally activated dissociation of cationized biodegradable polyesters

机译：阳离子化可生物降解聚酯的电子转移解离与碰撞活化解离

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摘要

Biodegradable polyesters were ionized by electrospray ionization and characterized by tandem mass spectrometry using collisionally activated dissociation (CAD) and electron transfer dissociation (ETD) as activation methods. The compounds studied include one homopolymer, polylactide and two copolymers, poly(ethylene adipate) and poly(butylene adipate). CAD of [M+2Na]~(2+) ions from these polyesters proceeds via charge-remote 1,5-H rearrangements over the ester groups, leading to cleavages at the (CO)O-alkyl bonds. ETD of the same precursor ions creates a radical anion at the site of electron attachment, which fragments by radical-induced cleavage of the (CO)O-alkyl bonds and by intramolecular nucleophilic substitution at the (CO)-O bonds. In contrast to CAD, ETD produces fragments in one charge state only and does not cause consecutive fragmentations, which simplifies spectral interpretation and permits conclusive identification of the correct end groups. The radical-site reactions occurring during ETD are very similar with those reported for ETD of protonated peptides. Unlike multiply protonated species, multiply sodiated precursors form ion pairs (salt bridges) after electron transfer, thereby promoting dissociations via nucleophilic displacement in addition to the radical-site dissociations typical in ETD.
机译：可生物降解的聚酯通过电喷雾电离进行离子化，并通过串联质谱法进行表征，其中使用碰撞活化解离（CAD）和电子转移解离（ETD）作为活化方法。所研究的化合物包括一种均聚物，聚丙交酯和两种共聚物，聚己二酸乙二酯和聚己二酸丁二酯。来自这些聚酯的[M + 2Na]〜（2+）离子的CAD通过酯基上的电荷远程1,5-H重排进行，导致在（CO）O-烷基键处裂解。相同前体离子的ETD在电子附着位点产生一个自由基阴离子，该自由基阴离子通过自由基诱导的（CO）O-烷基键裂解和在（CO）-O键上的分子内亲核取代而断裂。与CAD相比，ETD仅在一种电荷状态下产生片段，并且不会引起连续的片段化，这简化了光谱解释，并最终确定了正确的端基。 ETD期间发生的自由基位反应与质子化肽的ETD报道的非常相似。与多重质子化的物质不同，多重离子化的前体在电子转移后形成离子对（盐桥），因此除了ETD中典型的自由基位点解离外，还通过亲核取代促进了解离。

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