Ultraviolet photodissociation (UVPD) at 355 nm was used to rapidly identify peptides which had been chemically conjugated through bis-aryl hydrazone (BAH) moieties. The two biomolecules of interest were separately tagged to introduce either an aldehyde or a hydrazine and then conjugated together through these functional groups to from the UV-chromogenic BAH-group. In a mock mixture of peptides, UVPD was used to screen for the BAH-conjugated peptides in direct infusion ESI-UVPD-MS and online LC-UVPD-MS methods by comparing the abundances of the ions with the laser off and with the laser on. Only the BAH-conjugated peptides were observed to photodissociate upon exposure to UV irradiation, thus affording excellent selectivity for the pinpointing the relevant conjugated peptides in a complex mixture of nonconjugated peptides. UVPD analysis of conjugated model peptides indicated that the UVPD efficiencies of these species were charge state dependent. BAH-conjugated peptides that had a mobile proton which could protonate the basic BAH-moiety underwent more efficient photodissociation than the peptide ions with sequestered protons. Ultraviolet photodissociation of BAH-cross-linked peptides also yielded more diagnostic sequence ions than CID to unambiguously locate the site of conjugation.
利用波长为 355 纳米的紫外光解离(UVPD)来快速鉴定通过双芳基腙(
BAH)分子进行
化学共轭的肽。先分别标记两种相关
生物大分子,引入醛或
肼,然后通过这些官能团与紫外变色的
BAH 基团共轭。在模拟肽混合物中,通过比较激光关闭和激光打开时的离子丰度,在直接注入 ESI-UVPD-MS 和在线 LC-UVPD-MS 方法中使用 UVPD 筛选
BAH 共轭肽。观察到只有
BAH 共轭肽在紫外光照射下会发生光解离,从而为在复杂的非共轭肽混合物中精确定位相关共轭肽提供了极佳的选择性。对共轭模型肽的紫外分光光度分析表明,这些物种的紫外分光光度效率与电荷状态有关。与质子被螯合的肽离子相比,具有可移动质子并能与碱性
BAH 分子质子化的
BAH 共轭肽的光解离效率更高。与 CID 相比,
BAH 交联肽的紫外光解离也能产生更多的诊断序列离子,从而明确定位共轭部位。