Role of the site of protonation in the low-energy decompositions of gas-phase peptide ions
Role of the site of protonation in the low-energy decompositions of gas-phase peptide ions
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DOI：
10.1016/1044-0305(96)00019-0
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发表时间：
1996-06-01
影响因子：
3.2
通讯作者：
Whiting, A
中科院分区：
文献类型：
--
作者：
Cox, KA;Gaskell, SJ;Whiting, A
利用低能碰撞活化(CA)解离单个或多个质子化的多肽离子高度依赖于质子化的位置。多肽一级结构中强碱性氨基酸残基的存在决定了质子化的位置，这产生了相对于电荷位置基本均匀的前体离子群。试图用低能量的CA来解离这种类型的前体离子群体，会导致很少的途径导致很差的碎裂。本文所描述的工作代表了在低能CA实验中对一系列模型多肽的前驱离子群中电荷不均匀的影响的系统研究。例如，在肽RLC*IFSC*FR(其中C*表示半胱酸残基)中加入酸性残基可以平衡碱性精氨酸残基上的电荷，这使得电离质子能够驻留在沿着肽骨架的一些较不碱性的位置上。这导致前驱体离子群相对于电荷位置是不均匀的。这些离子的低能CA会导致不同的有效碎裂。分子模拟已经被用来证明能量优先构象包括精氨酸和半胱酸残基之间的离子内相互作用。
The dissociation of singly or multiply protonated peptide ions by using low-energy collisional activation (CA) is highly dependent on the sites of protonation. The presence of strongly basic amino acid residues in the peptide primary structure dictates the sites of protonation, which generates a precursor ion population that is largely homogeneous with respect to charge sites. Attempts to dissociate this type of precursor ion population by low-energy CA result in poor fragmentation via few pathways. The work described here represents a systematic investigation of the effects of charge heterogeneity in the precursor ion population of a series of model peptides in low-energy CA experiments. Incorporation of acidic residues in the peptide RLC*IFSC*FR (where C* indicates a cysteic acid residue), for example, balances the charge on the basic arginine residues, which enables the ionizing protons to reside on a number of less basic sites along the peptide backbone. This results in a precursor ion population that is heterogeneous with respect to charge site. Low-energy CA of these ions results in diverse and efficient fragmentation. Molecular modeling has been utilized to demonstrate that energetically preferred conformations incorporate an intraionic interaction between arginine and cysteic acid residues.