LifeTein successfully synthesized Aureocin A53, a highly cationic 51-residue peptide containing ten lysine and five tryptophan residues,   Formyl-MSWLNFLKYIAKYGKKAVSAAWKYKGKVLEWLNVGPTLEWVWQKLKKIAGL, using solid-phase peptide synthesis approach. A53 is a Class II bacteriocins. It was originally isolated from Staphylococcus aureus A53 and is active against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus. The mode of action was proposed as insertion into lipid bilayer and consequent membrane leakage. The solid-phase peptide synthesis provide an inexpensive alternative to isolation from bacteria culture or recombinant expression.