Merck, EMS0008, LysargiNase

LysargiNase is a metalloproteinase found in the thermophilic archaea Methanosarcina acetivorans. It specifically cleaves before lysine and arginine residues in proteins. This cleavage results in peptides with molecular weights similar to tryptic peptides, but with N-terminal lysine or arginine residues that can be fragmented with b ion-dominated spectra. This can improve protein C-terminal peptide identification and several arginine rich phosphosite assignments. Unlike with trypsin, LysargiNase cleavage also occurs at methylated lysine and arginine, allowing detection of these epigenetic modifications.