We present LysargiNase, an enzyme that cuts selectively before arginine and lysine residues. Unlike the commonly used trypsin, LysargiNase-generated peptides have N-terminal lysine or arginine residues leading to fragmentation spectra dominated by b-series ions. This improves protein C terminal–peptide identification and assignment of several arginine-rich phosphorylation sites. Notably, LysargiNase also cuts at methylated or dimethylated lysine and arginine, facilitating detection of these post-translational modifications.
Proteomics is the ideal tool to study proteases, the enzymes that sculpt the proteome. Positional proteomics allows us to zoom in on the peptides that reveal precise proteolytic cleavage sites, the N- or C-termini. To do so, we mainly use methods originally developed in Chris Overall´s laboratory: Terminal Amine Isotope Labeling of Substrates (TAILS) for the enrichment of N-termini and Carboxy-terminal amine-based isotope labeling of substrates (C-TAILS) for C-termini. Stable isotope labels are incorporated chemically during the workflow and enable relative quantification across several conditions, even from primary tissues.
Proteomic identification of cleavage sites (PICS) allows us to quickly obtain comprehensive information on the sequence specificity of any active recombinant protease of interest.
We are developing degradomics methods and are always interested in new applications to solve biological problems.