Hydrophobic Tagging-Assisted N-Termini Enrichment for In-Depth N-Terminome Analysis.

The analysis of protein N-termini is of great importance for understanding the protein function and elucidating the proteolytic processing. Herein, we develop a negative enrichment strategy, termed as hydrophobic tagging-assisted N-termini enrichment (HYTANE) to achieve a global N-terminome analysis. The HYTANE strategy showed a high efficiency in hydrophobic tagging and C18 material-assisted depletion using bovine serum albumin (BSA) as the sample. This strategy was applied to N-termini profiling from S. cerevisiae cell lysates and enabled the identification of 1096 protein N-termini, representing the largest N-terminome data set of S. cerevisiae. The identified N-terminal peptides accounted for 99% of all identified peptides, and no deficiency in acidic, histidine (His)-containing, and His-free N-terminal peptides was observed. The presented HYTANE strategy is therefore a highly selective, efficient, and unbiased strategy for the large scale N-terminome analysis. Furthermore, using the HYTANE strategy, we identified 329 cleavage sites and 291 substrates of caspases in Jurkat cells, demonstrating the great promise of HYTANE strategy for protease research. Data are available via ProteomeXchange with identifier PXD004690.