ORF56 derivatives and purity profile, zymogram, and bactericidal activity of Lys16. (a) Schematic representation of ORF56 and its N-terminal truncated forms. (b) SDS-PAGE profile of Lys16. Lane 1: molecular weight marker (97.5-14 kDa), Lane 2: purified Lys16 (5 μg). (c) Zymogram of purified Lys16 (5 μg) on autoclaved S aureus RN4220 cells. The muralytic activity of Lys16 is seen as a clear zone. (d) Bactericidal activity of Lys16. Purified Lys16 (100 μg/ml) reduced MRSA B911 viable CFUs by three orders of magnitude (99.9% cells killed).