Kostyukevich Yury, Kononikhin Alexey, Popov Igor, Spasskiy Alexander, Nikolaev Eugene
Institute for Energy Problems of Chemical Physics, Russian Academy of Sciences, Leninskij pr., 38k.2, 119334, Moscow, Russia; Moscow Institute of Physics and Technology, 141700, Dolgoprudnyi, Moscow Region, Russia; Skolkovo Institute of Science and Technology, Novaya St., 100, Skolkovo, 143025, Russian Federation.
J Mass Spectrom. 2015 Jan;50(1):49-55. doi: 10.1002/jms.3535.
Transition of proteins from the solution to the gas phase during electrospray ionization remains a challenging problem despite the large amount of attention it has received during the past few decades. One of the major questions relates to the extent to which proteins in the gas phase retain their condensed phase structures. We have used in-electrospray source hydrogen/deuterium exchange to determine the number of deuterium incorporations as a function of protein mass, charge state and temperature of the desolvating capillary where the reaction occurs. All experiments were performed on a Thermo LTQ FT Ultra equipped with a 7-T superconducting magnet. Ions were generated by an IonMax Electrospray ion source operated in the positive ESI mode. Deuterium exchange was performed by introducing a droplet of D2 O beneath the ESI capillary. We systematically investigated gas phase hydrogen/deuterium (H/D) exchange under atmospheric pressure for peptides and proteins of different molecular weights from 1 to 66 kDa. We observed that almost all proteins demonstrate similar exchange rates for all charge states and that these rates increase exponentially with the temperature of the desolvating capillary. We did not observe any clear correlation of the number of H/D exchanges with the value of the cross section for a corresponding charge state. We have demonstrated the possibility of performing in-ESI source H/D exchange of large proteins under atmospheric pressure. The simplicity of the experimental setup makes it a useful experimental technique that can be applied for the investigation of gas phase conformations of proteins.
尽管在过去几十年中受到了大量关注，但在电喷雾电离过程中蛋白质从溶液相转变到气相仍然是一个具有挑战性的问题。其中一个主要问题涉及气相中的蛋白质在多大程度上保留其凝聚相结构。我们使用电喷雾源内氢/氘交换来确定氘掺入的数量，作为蛋白质质量、电荷状态以及发生反应的去溶剂化毛细管温度的函数。所有实验均在配备7-T超导磁体的Thermo LTQ FT Ultra上进行。离子由在正ESI模式下运行的IonMax电喷雾离子源产生。通过在ESI毛细管下方引入一滴D2O来进行氘交换。我们系统地研究了大气压下不同分子量（1至66 kDa）的肽和蛋白质的气相氢/氘（H/D）交换。我们观察到，几乎所有蛋白质在所有电荷状态下都表现出相似的交换速率，并且这些速率随去溶剂化毛细管的温度呈指数增加。我们没有观察到H/D交换的数量与相应电荷状态的截面值之间有任何明显的相关性。我们已经证明了在大气压下对大蛋白质进行电喷雾源内H/D交换的可能性。实验装置的简单性使其成为一种有用的实验技术，可用于研究蛋白质的气相构象。
