Ion-Ion Reactions with Fixed-Charge Modified Proteins to Produce Ions in a Single, Very High Charge State.
Ion-Ion Reactions with Fixed-Charge Modified Proteins to Produce Ions in a Single, Very High Charge State.
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DOI：
10.1016/j.ijms.2008.07.029
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发表时间：
2008-10-01
影响因子：
1.8
通讯作者：
Smith LM
中科院分区：
文献类型：
--
作者：
Frey BL;Krusemark CJ;Ledvina AR;Coon JJ;Belshaw PJ;Smith LM
变性蛋白质的电喷雾电离（ESI）产生具有宽分布的多电荷离子的质谱。将固定的正电荷，特别是季铵基团，在其羧酸基团处连接到蛋白质上，与正模式ESI中相应的未修饰蛋白质相比，产生了显著更高的电荷状态。这些修饰的蛋白质与试剂阴离子的离子-离子反应通过质子转移导致电荷减少。这些质子转移反应不能从季铵基团去除电荷，季铵基团没有质子转移到阴离子。因此，人们可能期望电荷减少在等于修饰蛋白质上的固定电荷数的单个电荷状态处停止。然而，离子-离子反应产生的电荷状态低于这个固定电荷数，这是由于阴离子附着（加合）到蛋白质上。通过涉及气相碱的离子-分子反应的电荷还原也在低电荷状态下在改性蛋白质离子上产生加合物。通过保持离子处于远高于固定电荷数的电荷状态，可以避免这种加合物。在目前的工作中，蛋白质离子被选择性地“停泊”在离子阱质谱仪内的高电荷状态下，通过温和的射频激发，显着降低其离子-离子反应速率-一种称为“离子停泊”的技术。离子停放与固定电荷修饰的蛋白质的组合允许在单个非常高的电荷状态下产生大量离子。
Electrospray ionization (ESI) of denatured proteins produces a mass spectrum with a broad distribution of multiply charged ions. Attaching fixed positive charges, specifically quaternary ammonium groups, to proteins at their carboxylic acid groups generates substantially higher charge states compared to the corresponding unmodified proteins in positive-mode ESI. Ion-ion reactions of these modified proteins with reagent anions leads to charge reduction by proton transfer. These proton transfer reactions cannot remove charge from the quaternary ammonium groups, which do not have a proton to transfer to the anion. Thus, one might expect charge reduction to stop at a single charge state equal to the number of fixed charges on the modified protein. However, ion-ion reactions yield charge states lower than this number of fixed charges due to anion attachment (adduction) to the proteins. Charge reduction via ion-molecule reactions involving gas-phase bases also give adducts on the modified protein ions in low charge states. Such adducts are avoided by keeping the ions in charge states well above the number of fixed charges. In the present work protein ions were selectively “parked” within an ion trap mass spectrometer in a high charge state by mild radiofrequency excitation that dramatically slows their ion-ion reaction rate—a technique termed “ion parking”. The combination of ion parking with the fixed-charge modified proteins permits generation of a large population of ions in a single, very high charge state.
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影响因子：
7.4
作者：
Gunawardena, Harsha P.;Emory, Joshua F.;McLuckey, Scott A.
通讯作者：
McLuckey, Scott A.
影响因子：
7.4
作者：
McLuckey, SA;Reid, GE;Wells, JM
通讯作者：
Wells, JM
影响因子：
7.4
作者：
Reid, GE;Wu, J;McLuckey, SA
通讯作者：
McLuckey, SA
影响因子：
15
作者：
Stephenson, JL;McLuckey, SA
通讯作者：
McLuckey, SA
DOI：
10.1016/1044-0305(94)85011-9
发表时间：
1994-04-01
影响因子：
3.2
作者：
LOO, RRO;SMITH, RD
通讯作者：
SMITH, RD