Quadrupole ion mobility time-of-flight (Q-IM-TOF) mass spectrometers have revolutionized investigation of native biomolecular complexes. High pressures in the sources of these instruments aid transmission of protein complexes through damping of kinetic energy by collisional cooling. As adducts are removed through collisional heating (declustering), excessive collisional cooling can prevent removal of nonspecific adducts from protein ions, leading to inaccurate mass measurements, broad mass spectral peaks, and obfuscation of ligand binding. We show that reducing the source pressure using smaller aperture source sampling cones (SC) in a Waters Synapt G2-Si instrument increases protein ion heating by decreasing collisional cooling, providing a simple way to enhance removal of adducted salts from soluble proteins (GroEL 14-mer) and detergents from a transmembrane protein complex (heptameric Staphylococcus aureus α-hemolysin, αHL). These experiments are supported by ion heating and cooling simulations which demonstrate reduced collisional cooling at lower source pressures. Using these easily swapped sample cones of different apertures is a facile approach to reproducibly extend the range of activation in Synapt-type instruments.

中文翻译：

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在具有阶梯波源的 Synapt Q-IM-TOF 仪器上使用较小孔径源采样锥增加蛋白质复合物的碰撞激活。


四极杆离子淌度飞行时间 (Q-IM-TOF) 质谱仪彻底改变了天然生物分子复合物的研究。这些仪器源中的高压通过碰撞冷却阻尼动能来帮助蛋白质复合物的传输。由于加合物是通过碰撞加热（去簇）去除的，过度的碰撞冷却会阻止从蛋白质离子中去除非特异性加合物，从而导致质量测量不准确、质谱峰宽和配体结合混乱。我们表明，在 Waters Synapt G2-Si 仪器中使用较小孔径的源采样锥 (SC) 来降低源压力，可以通过减少碰撞冷却来增加蛋白质离子加热，从而提供了一种简单的方法来增强从可溶性蛋白质中去除加合盐 (GroEL 14- mer）和跨膜蛋白复合物（七聚金黄色葡萄球菌 α-溶血素，αHL）的去污剂。这些实验得到了离子加热和冷却模拟的支持，这些模拟证明了在较低源压力下减少了碰撞冷却。使用这些易于交换的不同孔径的样品锥体是一种简便的方法，可重复地扩展 Synapt 型仪器的激活范围。