Doublet N-Terminal Oriented Proteomics for N-Terminomics and Proteolytic Processing Identification.

The study of the N-terminome and the precise identification of proteolytic processing events are key in biology. Dedicated methodologies have been developed as the comprehensive characterization of the N-terminome can hardly be achieved by standard proteomics methods. In this context, we have set up a trimethoxyphenyl phosphonium (TMPP) labeling approach that allows the characterization of both N-terminal and internal digestion peptides in a single experiment. This latter point is a major advantage of our strategy as most N-terminomics methods rely on the enrichment of N-terminal peptides and thus exclude internal peptides.We have implemented a double heavy/light TMPP labeling and an automated data validation workflow that make our doublet N-terminal oriented proteomics (dN-TOP) strategy efficient for high-throughput N-terminome analysis.