CHARGE REMOTE FRAGMENTATION IN ECD AND ETD

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 中心，但不一定是研究者所在的机构。 主要的N-C？通过多电荷肽离子的电子捕获解离（ECD）或电子转移解离（ETD）的键断裂产生偶电子c+离子和奇电子z+离子，后者含有可引发二次断裂的自由基。这些二次碎片化都是电荷远程碎片化（CRF），因为它们不涉及带电研究中心的直接参与。由CRF产生的二级碎片离子对于肽结构分析非常有用，正如w-离子在异构体区分中的应用所证明的那样，但它们的存在也可能使光谱解释变得复杂。 本研究采用电子捕获检测法和电子迁移检测法研究了几种人工合成多肽的二级断裂。在ECD中，除了c和z+离子形成之外，z+离子的电荷远程片段化（CRF）是丰富的，导致内部片段形成或氨基酸的部分/整个侧链损失，有时远离主链切割位点的几个残基，并且在一定程度上导致多个侧链损失。 这些二级裂解被假定为在ECD中的初始骨架裂解之后，通过在氨基酸侧链的<$-、<$-或<$-位置处的氢提取而起始。 相比之下，ETD比ECD产生更少的CRF碎片，这可能是由于ETD中的碰撞冷却导致的z+离子中的小能量沉积和自由基的稳定化。 这种二次切割研究将有助于ECD/ETD谱的解释，并有助于从头测序和数据库搜索。这些结果发表在最近的J. Am。质谱学会文章.

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary N-C¿ bond cleavage by electron capture dissociation (ECD) or electron transfer dissociation (ETD) of a multiply charged peptide ion produces an even electron c ion and an odd electron z+ ion, the latter of which contains a radical which may initiate secondary fragmentations. These secondary fragmentations are all charge remote fragmentations (CRFs), because they do not involve the direct participation of a charged site. Secondary fragment ions generated by CRFs can be very useful for peptide structural analysis, as demonstrated by the utility of w-ions in isomer differentiation, but their presence may also complicate the spectral interpretation. In this study, secondary fragmentation of several synthetic peptides was studied by both ECD and ETD. In ECD, in addition to c and z+ ion formations, charge remote fragmentations (CRF) of z+ ions were abundant, resulting in internal fragment formation or partial/entire side chain losses from amino acids, sometimes several residues away from the backbone cleavage site, and to some extent multiple side chain losses. These secondary cleavages were postulated to be initiated by hydrogen abstraction at the ¿-, ¿-, or ¿-position of the amino acid side chain, after the initial backbone cleavage in ECD. In comparison, ETD generates fewer CRF fragments than ECD, possibly due to small energy deposition and stabilization of radicals in z+ ions by collisional cooling in ETD. This secondary cleavage study will facilitate ECD/ETD spectra interpretation, and help de novo sequencing and database searching. These results have been published in a recent J. Am. Soc. Mass Spectrom. article.