Tao Lei, McLean Janel R, McLean John A, Russell David H
The Laboratory for Biological Mass Spectrometry, Department of Chemistry, Texas A and M University, College Station, College Station, Texas, USA.
J Am Soc Mass Spectrom. 2007 Jul;18(7):1232-8. doi: 10.1016/j.jasms.2007.04.003. Epub 2007 Apr 15.
A database of ion-neutral collision cross-sections for singly-charged peptide ions is presented. The peptides included in the database were generated by enzymatic digestion of known proteins using three different enzymes, resulting in peptides that differ in terms of amino acid composition as well as N-terminal and C-terminal residues. The ion-neutral collision cross-sections were measured using ion mobility (IM) spectrometry that is directly coupled to a time-of-flight (TOF) mass spectrometer. The ions were formed by a matrix-assisted laser desorption ionization (MALDI) ion source operated at pressures (He bath gas) of 2 to 3 torr. The majority (63%) of the peptide ion collision cross-sections correlate well with structures that are best described as charge-solvated globules, but a significant number of the peptide ions exhibit collision cross-sections that are significantly larger or smaller than the average, globular mobility-mass correlation. Of the peptide ions having larger than average collision cross-sections, approximately 71% are derived from trypsin digestion (C-terminal Arg or Lys residues) and most of the peptide ions that have smaller (than globular) collision cross-sections are derived from pepsin digestion (90%).
本文介绍了一个单电荷肽离子的离子-中性碰撞截面数据库。该数据库中的肽是通过使用三种不同的酶对已知蛋白质进行酶解产生的，从而得到了在氨基酸组成以及N端和C端残基方面存在差异的肽。离子-中性碰撞截面是使用直接与飞行时间（TOF）质谱仪相连的离子淌度（IM）光谱法测量的。离子由在2至3托压力（氦浴气）下运行的基质辅助激光解吸电离（MALDI）离子源形成。大多数（63%）肽离子的碰撞截面与最能描述为电荷溶剂化球状体的结构具有良好的相关性，但相当数量的肽离子表现出的碰撞截面明显大于或小于平均球状淌度-质量相关性。在碰撞截面大于平均值的肽离子中，约71%来自胰蛋白酶消化（C端为精氨酸或赖氨酸残基），而大多数碰撞截面较小（小于球状）的肽离子来自胃蛋白酶消化（90%）。
