Recombinant Asp-N (rAsp-N), Mass Spec Grade, is a recombinant protease that cleaves protein N-terminal to aspartic acid residues. The enzyme was cloned from Stenotrophomonas maltophilia and purified from E. coli. rAsp-N is a highly active protease suitable for proteomic analysis of complex mixtures as well as peptide mapping of purified proteins such as therapeutic monoclonal antibodies. The protease is provided in 10µg aliquots in a conical-shaped vial for easy and consistent resuspension.