Shi Huilin, Atlasevich Natalya, Merenbloom Samuel I, Clemmer David E
J Am Soc Mass Spectrom. 2014 Dec;25(12):2000-8. doi: 10.1007/s13361-014-0834-y.
The solution dependence of gas-phase unfolding for ubiquitin M + 7H ions has been studied by ion mobility spectrometry-mass spectrometry (IMS-MS). Different acidic water:methanol solutions are used to favor the native (N), more helical (A), or unfolded (U) solution states of ubiquitin. Unfolding of gas-phase ubiquitin ions is achieved by collisional heating and newly formed structures are examined by IMS. With an activation voltage of 100 V, a selected distribution of compact structures unfolds, forming three resolvable elongated states (E1-E3). The relative populations of these elongated structures depend strongly on the solution composition. Activation of compact ions from aqueous solutions known to favor N-state ubiquitin produces mostly the E1 type elongated state, whereas activation of compact ions from methanol containing solutions that populate A-state ubiquitin favors the E3 elongated state. Presumably, this difference arises because of differences in precursor ion structures emerging from solution. Thus, it appears that information about solution populations can be retained after ionization, selection, and activation to produce the elongated states. These data as well as others are discussed.
通过离子淌度光谱-质谱联用技术（IMS-MS）研究了泛素M + 7H离子气相展开的溶液依赖性。使用不同的酸性水：甲醇溶液来促进泛素的天然（N）、更具螺旋结构（A）或展开（U）溶液状态。气相泛素离子的展开通过碰撞加热实现，新形成的结构通过IMS进行检测。在100 V的激活电压下，选定的紧密结构分布展开，形成三种可分辨的伸长状态（E1-E3）。这些伸长结构的相对丰度强烈依赖于溶液组成。从有利于N态泛素的水溶液中激活紧密离子主要产生E1型伸长状态，而从含有有利于A态泛素的甲醇溶液中激活紧密离子则有利于E3伸长状态。据推测，这种差异是由于溶液中出现的前体离子结构不同所致。因此，似乎关于溶液群体的信息在电离、选择和激活后可以保留下来以产生伸长状态。讨论了这些数据以及其他数据。
