Native mass spectrometry (MS) and surface induced dissociation (SID) have been applied to study the stoichiometry and quaternary structure of non-covalent protein complexes. In this study, Methanosarcina thermophila 20S proteasome, which consists of four stacked heptameric rings (α7β7β7α7 symmetry), has been selected to explore the SID dissociation pattern of a complicated stacked ring protein complex. SID produces both α and β subunits while collision induced dissociation (CID) produces only highly charged α subunit. In addition, the charge reduced 20S proteasome produces the α7β7 fragment, reflecting the stacked ring topology of the complex. The combination of SID and charge reduction is shown to be a powerful tool for the study of protein complex structure.

中文翻译：

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表面诱导解离产生嗜热甲烷八叠球菌 20S 蛋白酶体复合物的亚结构

本机质谱 (MS) 和表面诱导解离 (SID) 已被应用于研究非共价蛋白质复合物的化学计量和四级结构。在这项研究中，选择由四个堆叠七聚体环（α7β7β7α7 对称性）组成的 Methanosarcina thermophila 20S 蛋白酶体来探索复杂堆叠环蛋白复合物的 SID 解离模式。SID 产生 α 和 β 亚基，而碰撞诱导解离 (CID) 仅产生高电荷的 α 亚基。此外，电荷减少的 20S 蛋白酶体产生 α7β7 片段，反映了复合物的堆叠环形拓扑结构。SID 和电荷还原的结合被证明是研究蛋白质复合结构的有力工具。