Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712, United States.
J Am Chem Soc. 2012 Sep 26;134(38):15624-7. doi: 10.1021/ja3032086. Epub 2012 Sep 14.
Tyrosine deprotonation in peptides yields preferential electron detachment upon NETD or UVPD, resulting in prominent N-Cα bond cleavage N-terminal to the tyrosine residue. UVPD of iodo-tyrosine-modified peptides was used to generate localized radicals on neutral tyrosine side chains by homolytic cleavage of the C-I bond. Subsequent collisional activation of the radical species yielded the same preferential cleavage of the adjacent N-terminal N-Cα bond. LC-MS/MS analysis of a tryptic digest of BSA demonstrated that these cleavages are regularly observed for peptides when using high-pH mobile phases.
在 NETD 或 UVPD 过程中，肽中的酪氨酸去质子化会优先导致电子脱离，从而在酪氨酸残基的 N 端优先发生 N-Cα 键断裂。通过 C-I 键的均裂，对碘代酪氨酸修饰的肽进行 UVPD 可在中性酪氨酸侧链上生成局部自由基。随后，自由基的碰撞激活导致相邻 N 端 N-Cα 键的优先断裂。BSA 胰蛋白酶消化物的 LC-MS/MS 分析表明，在使用高 pH 流动相时，这些肽中的这些断裂经常被观察到。
