Substance P in the Gas Phase: Conformational Changes and Dissociations Induced by Collisional Activation in a Drift Tube
Substance P in the Gas Phase: Conformational Changes and Dissociations Induced by Collisional Activation in a Drift Tube
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DOI：
10.1007/s13361-019-02160-3
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发表时间：
2019-06-01
影响因子：
3.2
通讯作者：
Clemmer, David E.
中科院分区：
文献类型：
--
作者：
Conant, Christopher R.;Fuller, Daniel R.;Clemmer, David E.
下面介绍的工作与我们在这个问题上的配套文件，题为：P物质在解决方案：反式顺式构型变化的倒数第二脯氨酸启动非酶的肽键裂解。利用二维离子迁移谱（IMS-IMS）和质谱技术研究了P物质（subP）中[M+3 H]（3+）离子在气相中碰撞活化（CA）过程中的结构转变.在该方法中，在初始IMS分离之后选择具有指定迁移率的离子的不同构象，碰撞激活以产生新的构象，并且使用第二IMS区域再次分离这些产物结构。以这种方式，可以跟踪不同构象的折叠和展开转变。分析显示了五种构象的证据。与其他系统不同的是，每一个过渡都是不可逆的。作为激活电压的函数的研究用于在达到解离所需的能量之前辨别结构变化的途径。校准与转变的起始点相关的阈值，以获得不同结构之间的能量势垒的估计，并给出半定量势能图。总的来说，在没有溶剂的情况下，与[subP+3 H]（3+）的结构转变相关的势垒大约为40 kJmol（-1），大大低于乙醇溶液中某些类似结构转变所需的90 kJmol（-1）。在气相中的过渡能与热化学在溶液中类似的过渡的比较提供了线索，为什么禁止反向过渡。
The work presented below is related to our companion paper in this issue, entitled: Substance P in solution: trans-to-cis configurational changes of penultimate prolines initiate non-enzymatic peptide bond cleavages. Two-dimensional ion mobility spectrometry (IMS-IMS) and mass spectrometry techniques are used to investigate structural transitions for [M+3H](3+) ions of substance P (subP) upon collisional activation (CA) in the gas phase. In this approach, different conformations of ions having a specified mobility are selected after an initial IMS separation, collisionally activated to produce new conformers, and these product structures are separated again using a second IMS region. In this way, it is possible to follow folding and unfolding transitions of different conformations. The analysis shows evidence for five conformations. Unlike other systems, every transition is irreversible. Studies as a function of activation voltage are used to discern pathways of structural changes prior to reaching the energy required for dissociation. Thresholds associated with the onsets of transitions are calibrated to obtain estimates of the energetic barriers between different structures and semi-quantitative potential energy diagrams are presented. Overall, barriers associated with structural transitions of [subP+3H](3+) in the absence of solvent are on the order of 40kJmol(-1), substantially lower than the 90kJmol(-1) required for some similar structural transitions in solutions of ethanol. Comparisons of the transition energies in the gas phase with thermochemistry for similar transitions in solution provide clues about why reverse transitions are prohibited.