The non-enzymatic microbicidal activity of lysozymes

T4 lysozyme was thought to destroy bacteria by its muramidase activity, However, we demonstrate here that amphipathic helix stretches in the C-terminus of T4 lysozyme mediate its bactericidal and fungistatic activities. In heat-denatured T4 lysozyme, the enzymatic activity is completely abolished but unexpectedly, the antimicrobial functions remain preserved. Small synthetic peptides corresponding to amphipathic C-terminal domains of T4 lysozyme show a microbicidal activity. Its membrane disturbing activity was directly demonstrated for bacterial, fungal and plant cells but not in a hemolysis assay, Comparable results were obtained with hen egg white lysozyme, This opens up many new opportunities for optimization of lysozymes as antimicrobial agents in various applications by protein engineering, (C) 1999 Federation of European Biochemical Societies.