To better probe large biomolecular complexes, developments in mass spectrometry (MS) have focused on improving technologies used to generate, transmit, and measure high m/z ions. The additional tandem-MS (MSn) capabilities of ion trap mass spectrometers (ITMS) facilitate experiments that facilitate probing complex biomolecular ions. In particular, charge reduction using gas-phase ion/ion reactions increase separation of charge states generated via electrospray ionization (ESI), which increases confidence in charge state assignments and therefore masses determined from the observed charge states. Current ITMS technologies struggle to generate and measure low charge states of large (>50 kDa) proteins and complexes because of power limitations associated with conventional high-frequency sine wave operation. Other approaches, including frequency scanning techniques and use of digital waveforms, reduce or eliminate some of these limitations. The work presented here studies five different operational modes for a quadrupole ion trap (QIT) mass spectrometer used to generate and measure low charge states of bovine serum albumin (BSA), pyruvate kinase (PK), and GroEL. While digital operation of a QIT presents limitations during the ion/ion reaction period of the experiment, it generally provided the best spectra in terms of resolution and signal at m/z > 50,000.

中文翻译：

---

离子/离子反应的离子阱操作模式可产生高质荷比产物离子

为了更好地探测大型生物分子复合物，质谱 (MS) 的发展重点是改进用于生成、传输和测量高 m/z 离子的技术。离子阱质谱仪 (ITMS) 的额外串联质谱 (MSn) 功能促进了有助于探测复杂生物分子离子的实验。特别是，使用气相离子/离子反应减少电荷增加了通过电喷雾电离 (ESI) 产生的电荷态的分离，这增加了对电荷态分配的信心，从而增加了根据观察到的电荷态确定的质量。由于与传统高频正弦波操作相关的功率限制，当前的 ITMS 技术难以生成和测量大 (> 50 kDa) 蛋白质和复合物的低电荷状态。其他方法，包括频率扫描技术和数字波形的使用，减少或消除其中一些限制。此处介绍的工作研究了四极杆离子阱 (QIT) 质谱仪的五种不同操作模式，用于生成和测量牛血清白蛋白 (BSA)、丙酮酸激酶 (PK) 和 GroEL 的低电荷状态。虽然 QIT 的数字操作在实验的离子/离子反应期间存在局限性，但它通常在分辨率和 m/z > 50,000 的信号方面提供最佳光谱。和 GroEL。虽然 QIT 的数字操作在实验的离子/离子反应期间存在局限性，但它通常在分辨率和 m/z > 50,000 的信号方面提供最佳光谱。和 GroEL。虽然 QIT 的数字操作在实验的离子/离子反应期间存在局限性，但它通常在分辨率和 m/z > 50,000 的信号方面提供最佳光谱。