Zhang Haixia, Yeung Ken K-C
Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7.
Anal Chem. 2004 Nov 15;76(22):6814-8. doi: 10.1021/ac049230c.
A simple way to selectively isolate peptides based on their isoelectric points (pI) for MALDI mass spectral analysis is described. An applied voltage was used to electromigrate peptides into a capillary. The capillary was modified with a zwitterionic surfactant, 1,2-dilauroyl-sn-phosphatidylcholine (DLPC), to suppress the electroosmotic flow (EOF) during injection. Hence, either the cationic or the anionic peptides were introduced, depending on the voltage polarity. By controlling the pH, selective loading of peptides was performed to isolate trace components from a mixture. The injected sample plugs were subsequently spotted in nanoliter volumes for MALDI-MS analysis. No significant sample losses resulting from selective sampling were detected. Low attomole-level detection of peptides (adrenocorticotropic hormone fragment 18-39, pI 4.25) was achieved from a mixture containing other peptides (angiotensin I, pI 6.92, and bradykinin, pI 12.00) at 100 000-fold higher concentrations.
本文描述了一种基于等电点（pI）选择性分离肽段用于基质辅助激光解吸电离质谱（MALDI-MS）分析的简单方法。施加电压使肽段电迁移进入毛细管。毛细管用两性离子表面活性剂1,2-二月桂酰-sn-磷脂酰胆碱（DLPC）进行修饰，以抑制进样过程中的电渗流（EOF）。因此，根据电压极性，阳离子肽或阴离子肽被引入。通过控制pH值，进行肽段的选择性加载，以从混合物中分离痕量成分。随后将注入的样品塞以纳升级体积点样用于MALDI-MS分析。未检测到因选择性采样导致的显著样品损失。从含有浓度高100000倍的其他肽段（血管紧张素I，pI 6.92和缓激肽，pI 12.00）的混合物中实现了低至阿托摩尔水平的肽段（促肾上腺皮质激素片段18 - 39，pI 4.25）检测。
