Electrospray ionization mass spectrometry has been used to study protein interactions driven by noncovalent forces. The gentleness of the electrospray ionization process allows intact protein complexes to be directly detected by mass spectrometry. Evidence from the growing body of literature suggests that the ESI-MS observations for these weakly bound systems reflect, to some extent, the nature of the interaction found in the condensed phase. Stoichiometry of the complex can be easily obtained from the resulting mass spectrum because the molecular weight of the complex is directly measured. For the study of protein interactions, ESI-MS is complementary to other biophysical methods, such as NMR and analytical ultracentrifugation. However, mass spectrometry offers advantages in speed and sensitivity. The experimental variables that play a role in the outcome of ESI-MS studies of noncovalently bound complexes are reviewed. Several applications of ESI-MS are discussed, including protein interactions with metal ions and nucleic acids and subunit protein structures (quaternary structure).

中文翻译：

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通过电喷雾电离质谱研究非共价蛋白复合物。

电喷雾电离质谱已用于研究由非共价力驱动的蛋白质相互作用。电喷雾电离过程的温和性使得完整的蛋白质复合物可以通过质谱直接检测。越来越多的文献证据表明，对这些弱结合系统的ESI-MS观测在一定程度上反映了在凝聚相中发现的相互作用的性质。由于直接测量复合物的分子量，因此可以容易地从所得质谱图中获得复合物的化学计量。为了研究蛋白质相互作用，ESI-MS是其他生物物理方法（例如NMR和分析超速离心）的补充。然而，质谱法在速度和灵敏度方面具有优势。审查了在非共价结合复合物的ESI-MS研究结果中起作用的实验变量。讨论了ESI-MS的几种应用，包括与金属离子和核酸的蛋白质相互作用以及亚基蛋白质结构（四级结构）。