Conformations of biopolymers in the gas phase: a new mass spectrometric method
Conformations of biopolymers in the gas phase: a new mass spectrometric method
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DOI：
10.1016/s1387-3806(99)00256-0
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发表时间：
2000-01-21
影响因子：
1.8
通讯作者：
Bowers, MT
中科院分区：
文献类型：
--
作者：
Gill, AC;Jennings, KR;Bowers, MT
本文提出了一种气相生物分子碰撞截面的测量方法，该方法采用一种稍作改进的商用三重四极杆仪器。修改允许精确的停止电位测量离子退出的碰撞区域的仪器。一个简单的模型可以将这些曲线转换成横截面。为了考虑某些定义不明确的实验参数（精确离子能量、碰撞单元中的绝对压力等），模型中包含了可变参数。通过将结果归一化到众所周知的单电荷缓激素的横截面，这些参数是根据具体情况确定的。研究了两个相对较大的系统（细胞色素c和肌红蛋白），因此可以与文献值进行比较。然后在9 -14个残基范围内研究了一些新的肽体系。其中包括黄体生成素释放激素（LHRH）物质P的单离子和双离子，以及除缓激肽外的bombesin。实验横截面与广泛的分子动力学模型的预测非常吻合。一个有趣的结果是，实验观察到LHRH、P物质和bombesin的双带电离子的横截面都比相应的单带电离子的横截面小。分子动力学没有重现这一结果，预测双电荷的横截面与单电荷的横截面相同或略大。然而，实验结果似乎是正确的。对于多电荷离子的建模过程中可能存在的缺陷被认为可能是造成这种差异的原因。(C) 2000爱思唯尔科学有限公司
A method is developed for measuring collision cross sections of gas-phase biomolecules using a slightly modified commercial triple quadrupole instrument. The modifications allow accurate stopping potentials to be measured for ions exiting the collision region of the instrument. A simple model allows these curves to be converted to cross sections. In order to account for certain poorly defined experimental parameters (exact ion energy, absolute pressure in the collision cell, etc.) variable parameters are included in the model. These parameters are determined on a case by case basis by normalizing the results to the well known cross section of singly charged bradykinin, Two relatively large systems were studied (cytochrome c and myoglobin) so comparisons could be made to literature values. A number of new peptide systems were then studied in the 9 -14 residue range. These included singly and doubly charged ions of luteinizing hormone releasing hormone (LHRH) substance P, and bombesin in addition to bradykinin. The experimental cross sections were in very good agreement with predictions from extensive molecular dynamics modeling. One interesting result was the experimental observation that the cross section of the doubly charged ions of LHRH, substance P, and bombesin were all smaller than those of the corresponding singly charged ions. Molecular dynamics did not reproduce this result, predicting doubly charged cross sections of the same magnitude or slightly larger than for the singly charged species. The experimental results appear to be correct, however. Possible shortcomings in the modeling procedure for multiply charged ions were suggested that might account for the discrepancy. (C) 2000 Elsevier Science B.V.