FAQ: I digested BSA with Endoproteinase AspN following standard conditions and examined the released fragments with Mass-spec. I did not see many peaks that matched the predicted fragment but saw a lot of unpredicted bands, perhaps indicating non-specific enzyme activity.

This is more likely a case of poor or no digestion than non-specific digestion as our Endoproteinase AspN works best with peptides. Alternatively, you can do a "double digest": digest your protein first with Trypsin or Endoproteinase GluC to get it down to a smaller size, followed by or in combination with an Endoproteinase AspN digestion to generate peptides with N-terminal Aspartic acid.