A comparison of positive and negative ion collision-induced dissociation for model heptapeptides with one basic residue.
A comparison of positive and negative ion collision-induced dissociation for model heptapeptides with one basic residue.
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具有一个碱性残基的模型七肽的正离子和负离子碰撞诱导解离的比较。
DOI：
10.1002/jms.1715
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Cassady,CarolynJ
中科院分区：
文献类型：
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作者：
Pu,Dan;Clipston,NigelL;Cassady,CarolynJ
在正负模式下探讨了碱性残基的特性和位置对肽解离的影响。对以下类型的单质子化和去质子化七肽进行低能碰撞诱导解离 (CID)：XAAAAAA、AAAXAAA、AAAAAXA 和 AAAAAAX，其中 X 是精氨酸 (R)、赖氨酸 (K) 或组氨酸 (H) 残基，A 是丙氨酸。对于 [M + H]+，CID 谱图以邻近碱性残基的裂解为主，并且大多数产物离子包含碱性残基。碱性残基对 [M + H]+ 断裂影响的顺序是精氨酸 > 组氨酸 ≈ 赖氨酸，这也是这些氨基酸气相碱性降低的顺序。这些结果与作为正离子电荷位点的碱性残基的侧链以及具有更高的正电荷保留（即隔离）的更碱性的精氨酸残基一致。相反，对于 [M – H]- 碱性残基的身份和位置对主链断裂几乎没有影响。这与碱性残基不是负模式电荷位点是一致的。对于这些肽，可以在负模式下找到更完整的主链片段系列，这对于未知物的测序很重要。两个极性的光谱都包含 C 端 y-离子，但 yn"+ 比相应的 yn- 多两个氢。另一个主要区别是在正模式下产生 N 端骨干系列 bn+，在负模式下产生 cn−。因此，比较正负离子光谱，重点搜索相差 2 Da (yn″+vsyn−) 和 15 Da (bn+vscn−) 的离子对，可能是确定产物离子是从肽的 C 末端还是 N 末端生成的有用方法。此外，对于去质子化的肽，观察到从精氨酸残基中消除 NH→C→NH 的特征。版权所有 © 2010 约翰威利父子有限公司
The effects of the identity and position of basic residues on peptide dissociation were explored in the positive and negative modes. Low‐energy collision‐induced dissociation (CID) was performed on singly protonated and deprotonated heptapeptides of the type: XAAAAAA, AAAXAAA, AAAAAXA and AAAAAAX, where X is arginine (R), lysine (K) or histidine (H) residues and A is alanine. For [M + H]+, the CID spectra are dominated by cleavages adjacent to the basic residues and the majority of the product ions contain the basic residues. The order of a basic residue's influence on fragmentation of [M + H]+is arginine > histidine ≈ lysine, which is also the order of decreasing gas‐phase basicity for these amino acids. These results are consistent with the side chains of basic residues being positive ion charge sites and with the more basic arginine residues having a higher retention (i.e. sequestering) of the positive charge. In contrast, for [M − H]−the identity and position of basic residues has almost no effect on backbone fragmentation. This is consistent with basic residues not being negative mode charge sites. For these peptides, more complete series of backbone fragments, which are important in the sequencing of unknowns, can be found in the negative mode. Spectra at both polarities contain C‐terminal y‐ions, but yn″+has two more hydrogens than the corresponding yn−. Another major difference is the production of the N‐terminal backbone series bn+in the positive mode and cn−in the negative mode. Thus, comparison of positive and negative ion spectra with an emphasis on searching for pairs of ions that differ by 2 Da (yn″+vsyn−) and by 15 Da (bn+vscn−) may be a useful method for determining whether a product ion is generated from the C‐terminal or the N‐terminal end of a peptide. In addition, a characteristic elimination of NHCNH from arginine residues is observed for deprotonated peptides. Copyright © 2010 John Wiley & Sons, Ltd.