Antibacterial peptide with potent activity against both Gram-positive and Gram-negative bacteria (PubMed:22586077). May kill bacteria via an intracellular action mode to affect protein folding (PubMed:22586077). Does not show effects on tested filamentous fungi or on the yeast S.cerevisiae (PubMed:22586077). Does not act by destroying the membrane integrity, which is consistent with its nonamphiphilic architecture (PubMed:22586077). Acts more rapidly than vancomycin, suggesting it does not act by inhibiting cell-wall biosynthesis (PubMed:22586077). Does not cause hemolysis and has no cytotoxic effect on HEK cells (PubMed:22586077, PubMed:27084888). In vivo, is as efficient as vancomycin to protect mouse peritonitis models from S.aureus and P.aeruginosa infections (PubMed:22586077). Has the structural arrangement of an alpha-helix connected to a beta-sheet by disulfide bonds (CSalpha/beta). The Cys-47-Pro-48 bond adopts an unusual cis conformation. Belongs to the invertebrate defensin family. Micasin should not be confused with micasin-1, the second defensin-like peptide from A.canis, which shows low sequence similarity compared to micasin.