Department of Molecular Pharmacology, National Cerebral and Cardiovascular Center, Osaka 565-8565, Japan.
Proteomics Laboratory, Isotope Science Center, The University of Tokyo, Tokyo 113-0032, Japan.
Biochem Biophys Res Commun. 2020 Dec 17;533(4):872-878. doi: 10.1016/j.bbrc.2020.09.056. Epub 2020 Sep 29.
Proteolytic cleavage at specific sites is a key event that modulates protein functions in biological processes. These cleavage sites are identified through mass spectrometry-based peptidomics of overlapping peptide sequences. Here, we assessed to what extent a recent capillary electrophoresis (CE) system interfaced with electrospray ionization-mass spectrometry (ESI-MS) contributes to identifying endogenous peptides present in a biological sample. Peptides released by a human endocrine cell line stimulated for secretion was analyzed for uncovering potential processing sites created by proprotein convertases (PCs) that cleave precursors in the secretory pathway. CE-ESI-MS was conducted, in comparison to a standard liquid chromatography (LC)-ESI-MS platform. LC and CE complemented each other in elucidating processing sites that match PC consensus sequences from known substrates. We suggest that the precursors BIGH3, STC1, LFNG, QSOX1 and CYTC are potential substrates for PCs, and that a CE-ESI system would come in handy and garner greater recognition as a robust tool in peptidomics.
蛋白水解在特定的位点进行，是调节生物过程中蛋白质功能的关键事件。这些切割位点是通过基于质谱的重叠肽序列的肽组学来鉴定的。在这里，我们评估了最近的毛细管电泳（CE）系统与电喷雾电离-质谱（ESI-MS）接口在多大程度上有助于鉴定存在于生物样品中的内源性肽。分析了受刺激分泌的人内分泌细胞系释放的肽，以揭示由在分泌途径中切割前体的蛋白原转化酶（PCs）产生的潜在加工位点。进行了 CE-ESI-MS 分析，并与标准的液相色谱（LC）-ESI-MS 平台进行了比较。LC 和 CE 相互补充，阐明了与已知底物的 PC 共有序列匹配的加工位点。我们认为，BIGH3、STC1、LFNG、QSOX1 和 CYTC 等前体可能是 PCs 的底物，CE-ESI 系统将成为肽组学中一种强大的工具，并得到更广泛的认可。
