We describe instrumentation for conducting tandem surface-induced dissociation (tSID) of native protein complexes on an ultrahigh resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The two stages of SID are accomplished with split lenses replacing the entrance lenses of the quadrupole mass filter (stage 1, referred to herein as SID-Q) and the collision cell (stage 2, Q-SID). After SID-Q, the scattered projectile ions and subcomplexes formed in transit traverse the pre-filter prior to the mass-selecting quadrupole, providing preliminary insights into the SID fragmentation kinetics of noncovalent protein complexes. The isolated SID fragments (subcomplexes) are then fragmented by SID in the collision cell entrance lens (Q-SID), generating subcomplexes of subcomplexes. We show that the ultrahigh resolution of the FT-ICR can be used for deconvolving species overlapping in m/z, which are particularly prominent in tandem SID spectra due to the combination of symmetric charge partitioning and narrow product ion charge state distributions. Various protein complex topologies are explored, including homotetramers, homopentamers, a homohexamer, and a heterohexamer.

我们描述了在超高分辨率傅里叶变换离子回旋共振 (FT-ICR) 质谱仪上进行天然蛋白质复合物串联表面诱导解离 (tSID) 的仪器。SID 的两个阶段是用分裂透镜代替四极滤质器（阶段 1，本文称为 SID-Q）和碰撞池（阶段 2，Q-SID）的入口透镜来完成的。在 SID-Q 之后，在运输过程中形成的分散的抛射物离子和亚复合物在质量选择四极杆之前穿过预过滤器，从而初步了解非共价蛋白复合物的 SID 碎裂动力学。然后，分离的 SID 片段（子复合体）在碰撞池入口透镜 (Q-SID) 中由 SID 分段，生成子复合体的子复合体。m/z，由于对称电荷分配和窄产物离子电荷态分布的结合，在串联 SID 光谱中尤为突出。探索了各种蛋白质复合物拓扑结构，包括同四聚体、同五聚体、同六聚体和异六聚体。