Rapid Online Non-Enzymatic Protein Digestion Analysis with High Pressure Superheated ESI-MS
Rapid Online Non-Enzymatic Protein Digestion Analysis with High Pressure Superheated ESI-MS
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DOI：
10.1007/s13361-015-1111-4
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发表时间：
2015-07-01
影响因子：
3.2
通讯作者：
Hiraoka, Kenzo
中科院分区：
文献类型：
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作者：
Chen, Lee Chuin;Kinoshita, Masato;Hiraoka, Kenzo
最近，我们报道了一种新的ESI离子源，其可以电喷雾液体温度远高于正常沸点的过热水溶液（J. Am.质谱学会25，1862-1869）。通过将离子源加压到大于大气压的压力来防止液体沸腾。我们之前的原型中的最大操作压力为11个大气压，可实现的最高温度为180摄氏度。在本文中，一个更紧凑的原型，可以操作高达27大气压和250摄氏度的液体温度的构造，和可重复的MS采集可以扩展到以前从未被测试过的电喷雾温度。在这里，我们将这种过热的ESI源应用于快速在线蛋白质消化MS。当样品溶液流过加热的ESI毛细管时，样品溶液被快速加热，当溶液从加热的毛细管尖端出现时，消化产物被ESI原位电离。以甲酸等弱酸为溶剂，热加速消化（酸水解）在天冬氨酸（Asp，D）残基位点具有选择性裂解。液体在有效加热区内的停留时间约为20秒。在线操作消除了从消化反应器转移样品的需要，并且消化反应的输出可以通过溶液流速和加热器温度以接近实时的方式进行监测和操纵。
Recently, we reported a new ESI ion source that could electrospray the super-heated aqueous solution with liquid temperature much higher than the normal boiling point (J. Am. Soc. Mass Spectrom. 25, 1862-1869). The boiling of liquid was prevented by pressurizing the ion source to a pressure greater than atmospheric pressure. The maximum operating pressure in our previous prototype was 11atm, and the highest achievable temperature was 180 degrees C. In this paper, a more compact prototype that can operate up to 27atm and 250 degrees C liquid temperatures is constructed, and reproducible MS acquisition can be extended to electrospray temperatures that have never before been tested. Here, we apply this super-heated ESI source to the rapid online protein digestion MS. The sample solution is rapidly heated when flowing through a heated ESI capillary, and the digestion products are ionized by ESI in situ when the solution emerges from the tip of the heated capillary. With weak acid such as formic acid as solution, the thermally accelerated digestion (acid hydrolysis) has the selective cleavage at the aspartate (Asp, D) residue sites. The residence time of liquid within the active heating region is about 20s. The online operation eliminates the need to transfer the sample from the digestion reactor, and the output of the digestive reaction can be monitored and manipulated by the solution flow rate and heater temperature in a near real-time basis.