CHARGE REMOTE FRAGMENTATION IN ECD AND ETD

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 多电荷多肽离子的电子俘获解离(ECD)或电子转移解离(ETD)导致初级N-C~+键断裂，产生一个偶数电子c离子和一个奇数电子z+离子，后者含有可能引发二次碎裂的自由基。这些二次碎裂都是电荷远程碎裂(CRF)，因为它们不涉及带电部位的直接参与。CRF产生的次级碎片离子对多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复杂化。 本研究用电子捕获检测器和电子捕获检测器研究了几种合成肽的二次碎裂。在ECD中，除了c和z+离子的形成外，z+离子的电荷远程碎裂(CRF)丰富，导致氨基酸的内部碎片形成或部分或全部侧链丢失，有时远离主干裂解位点的几个残基，以及一定程度上的多个侧链丢失。这些次级裂解被认为是在ECD中最初的骨架裂解之后，由氨基酸侧链的？-、？-或？-位的氢夺取而开始的。相比之下，ETD产生的CRF碎片比ECD少，这可能是由于ETD中碰撞冷却对z+离子中自由基的稳定和能量的沉积。这种二级切割研究将有助于ECD/ETD谱的解释，并有助于从头测序和数据库搜索。这些研究结果发表在最近的《美国医学会杂志》上。SoC。质谱学。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.