Shattering of peptide ions on self-assembled monolayer surfaces
Shattering of peptide ions on self-assembled monolayer surfaces
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DOI：
10.1021/ja027915t
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发表时间：
2003-02-12
影响因子：
15
通讯作者：
Futrell, JH
中科院分区：
文献类型：
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作者：
Laskin, J;Bailey, TH;Futrell, JH
利用傅里叶变换离子回旋共振质谱仪(FT-ICR MS)研究了DES-Arg(1)和Des-Arg(9)-Bradykinin在氟化自组装单分子膜(SAM)表面的时间分辨和碰撞能量分辨表面诱导解离(SID)。时间分辨破碎效率曲线(TFEC)是由我们实验室开发的基于RRKM的方法模拟的，该方法利用非常灵活的内能沉积函数的解析表达式，能够再现气相中的单碰撞和多碰撞激活以及通过与表面的碰撞激发。实验观察和模拟都在离子-表面相互作用的动力学中建立了一个非常尖锐的转变：碎裂转变。这种转变的实验特征是出现了瞬间(与时间无关的)碎裂，这种碎裂在高碰撞能量时占主导地位。碎裂打开了各种解离途径，这些途径是慢碰撞和热离子活化无法进入的。这导致对单质子化多肽的序列覆盖比任何缓慢激活方法获得的解离模式要好得多。模拟表明，对于较短的反应延迟，这些多肽的解离完全由碎裂决定。DES-Arg(1)和Des-Arg(9)-Bradykinin的碎裂转变所需的内能大致相同，导致在较短的反应延迟下获得的碎裂效率曲线重叠。在较长的延迟时间内，DES-Arg(1)和DES-Arg(9)-缓激肽的裂解效率曲线发散，母体离子的耗竭主要由较慢的衰减率决定。时间分辨数据的RRKM模拟得到DES-Arg1和DES-Arg(9)-Bradykinin的解离阈值分别为1.17和1.09 eV，活化熵分别为-22.2和-23.3卡/(摩尔K)。Des-Arg(1)-缓激肽的解离参数与热实验参数符合得很好。然而，本研究得到的DES-Arg9-Bradykinin的热数据和解离参数之间存在着显著的差异。这种差异归因于构象的不同，这些构象在解离之前经历了热激活和离子-表面碰撞激活。
Time- and collision energy-resolved surface-induced dissociation (SID) of des-Arg(1)- and des-Arg(9)-bradykinin on a fluorinated self-assembled monolayer (SAM) surface was studied by use of a novel Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) specially equipped to perform SID experiments. Time-resolved fragmentation efficiency curves (TFECs) were modeled by an RRKM-based approach developed in our laboratory that utilizes a very flexible analytical expression for the internal energy deposition function capable of reproducing both single- and multiple-collision activation in the gas phase and excitation by collisions with a surface. Both experimental observations and modeling establish a very sharp transition in the dynamics of ion-surface interaction: the shattering transition. The experimental signature for this transition is the appearance of prompt (time-independent) fragmentation, which becomes dominant at high collision energies. Shattering opens a variety of dissociation pathways that are not accessible to slow collisional and thermal ion activation. This results in much better sequence coverage for the singly protonated peptides than dissociation patterns obtained with any of the slow activation methods. Modeling demonstrated that, for short reaction delays, dissociation of these peptides is solely determined by shattering. Internal energies required for shattering transition are approximately the same for des-Arg(1) and des-Arg(9)-bradykinin, resulting in the overlap of fragmentation efficiency curves obtained at short reaction delays. At longer delay times, parent ions depletion is mainly determined by a slow decay rate and fragmentation efficiency curves for des-Arg(1) and des-Arg(9)-bradykinin diverge. Dissociation thresholds of 1.17 and 1.09 eV and activation entropies of -22.2 and -23.3 cal/(mol K) were obtained for des-Arg1 and des-Arg(9)-bradykinin from RRKM modeling of time-resolved data. Dissociation parameters for des-Arg(1)-bradykinin are in good agreement with parameters derived from thermal experiments. However, there is a significant discrepancy between the thermal data and dissociation parameters for des-Arg9-bradykinin obtained in this study. The difference is attributed to the differences in conformations that undergo thermal activation and activation by ion-surface collisions prior to dissociation.