Infrared multiphoton dissociation (IRMPD) of N-terminal sulfonated peptides improves de novo sequencing capabilities in a quadrupole ion trap mass spectrometer. Not only does IRMPD promote highly efficient dissociation of the N-terminal sulfonated peptides but also the entire series of y ions down to the y1 fragment may be detected due to alleviation of the low-mass cutoff problem associated with conventional collisional activated dissociation (CAD) methods in a quadrupole ion trap. Commercial de novo sequencing software was applied for the interpretation of CAD and IRMPD MS/MS spectra collected for seven unmodified peptides and the corresponding N-terminal sulfonated species. In most cases, the additional information obtained by N-terminal sulfonation in combination with IRMPD provided significant improvements in sequence identification. The software sequence tag results were combined with a commercial database searching algorithm to interpret sequence information of a tryptic digest on α-casein s1. Energy-variable CAD studies confirmed a 30−40% reduction in the critical energies of the N-terminal sulfonated peptides relative to unmodified peptides. This reduction in dissociation energy facilitates IRMPD in a quadrupole ion trap.
N 端磺化肽的红外多光子解离 (IR
MPD) 提高了四极离子阱质谱仪中的从头测序能力。 IR
MPD 不仅可以促进 N 端磺化肽的高效解离,而且由于缓解了与传统碰撞激活解离 (CAD) 相关的低质量截断问题,因此可以检测到 y1 片段的整个 y 离子系列四极离子阱中的方法。应用商业从头测序软件来解释为七种未修饰的肽和相应的 N 末端
磺化物质收集的 CAD 和 IR
MPD MS/MS 谱。在大多数情况下,通过 N 端磺化与 IR
MPD 结合获得的附加信息显着改善了序列识别。软件序列标签结果与商业数据库搜索算法相结合,以解释 α-
酪蛋白 s1 胰
蛋白酶消化的序列信息。能量可变 CAD 研究证实,相对于未修饰的肽,N 端磺化肽的临界能量降低了 30−40%。解离能的降低有利于四极离子阱中的 IR
MPD。