Capillary electrophoresis electrospray ionization-mass spectrometry for peptidomics-based processing site...

Area of Science:

• Biochemistry
• Proteomics
• Analytical Chemistry

Background:

• Proteolytic cleavage is crucial for protein function regulation in biological processes.
• Mass spectrometry-based peptidomics using overlapping peptides is the standard for identifying protein cleavage sites.
• Proprotein convertases (PCs) are key enzymes involved in protein precursor processing within the secretory pathway.

Purpose of the Study:

• To evaluate the contribution of a capillary electrophoresis (CE) system interfaced with electrospray ionization-mass spectrometry (CE-ESI-MS) for identifying endogenous peptides.
• To uncover potential protein processing sites generated by proprotein convertases (PCs) in a human endocrine cell line.
• To compare the efficacy of CE-ESI-MS with standard liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) in peptidomics.

Main Methods:

• Analysis of peptides released from a stimulated human endocrine cell line using CE-ESI-MS.
• Comparative analysis with peptides analyzed by a standard LC-ESI-MS platform.
• Identification of cleavage sites matching proprotein convertase consensus sequences.

Main Results:

• CE-ESI-MS successfully identified endogenous peptides in biological samples.
• Both LC and CE platforms complemented each other in elucidating protein processing sites.
• Identified processing sites were consistent with known proprotein convertase (PC) substrate consensus sequences.

Conclusions:

• The CE-ESI-MS system is a valuable and robust tool for peptidomics analysis.
• BIGH3, STC1, LFNG, QSOX1, and CYTC are suggested as potential substrates for proprotein convertases (PCs).
• CE-ESI-MS offers complementary advantages for identifying protein processing sites and enzyme substrates.