Graduate School of Nanobioscience, Yokohama City University, Yokohama, Japan.
J Am Soc Mass Spectrom. 2010 Dec;21(12):1979-88. doi: 10.1016/j.jasms.2010.08.009. Epub 2010 Aug 21.
Although conventional N-Cα bond cleavage in electron capture dissociation (ECD) of multiply-charged peptides generates a complementary c' and z(·) fragment pair, the N-Cα cleavage followed by hydrogen transfer from c' to z(·) fragments produces other fragments, namely c(·) and z'. In this study, the influence of charge state and amino acid composition on hydrogen transfer in ECD is described using sets of peptides. Hydrogen transferred ionic species such as c(·) and z' were observed in ECD spectra of doubly-protonated peptides, while the triply-protonated form did not demonstrate hydrogen transfer. The extent of hydrogen transfer in ECD of doubly-protonated peptides was dependent on constituent amino acids. The ECD of doubly-protonated peptides possessing numerous basic sites showed extensive hydrogen transfer compared with ECD of less basic peptides. The extent of hydrogen transfer is discussed from the viewpoints of the structure of peptide ions, the possibility of internal hydrogen bonding and intermediate lifetime of complex [c' + z(·)].
尽管在多电荷肽的电子捕获解离（ECD）中，常规的 N-Cα 键断裂会产生互补的 c' 和 z(·) 片段对，但 N-Cα 断裂后，c' 向 z(·) 片段转移氢会产生其他片段，即 c(·) 和 z'。在这项研究中，使用肽组描述了电荷状态和氨基酸组成对 ECD 中氢转移的影响。在双重质子化肽的 ECD 光谱中观察到了氢转移离子物种，如 c(·) 和 z'，而三重质子化形式则没有发生氢转移。在 ECD 中，双重质子化肽的氢转移程度取决于组成氨基酸。具有多个碱性位点的双重质子化肽的 ECD 与碱性较弱的肽的 ECD 相比，氢转移程度较大。从肽离子结构、内部氢键的可能性以及复合物[c' + z(·)]的中间寿命的角度讨论了氢转移的程度。
