Alysozyme is a part of theinnate immune system.^[1] They areenzymes which are inmucus secretions likesaliva. They protect againstinfection by chopping up thebacteria,viruses andfungi which infect animals.

The name 'lysozyme' was coined in 1922 byAlexander Fleming (1881–1955), the discoverer ofpenicillin.^[2] Fleming first observed the antibacterial action of lysozyme when he treated bacterial cultures with nasal mucus from a patient suffering from acommon cold.^[2]

Lysozyme is in a number of secretions, such astears, saliva,milk, andmucus. It is also present incytoplasmicgranules ofmacrophages andgranulocyteneutrophils.

The enzyme works by attackingpolymers in the cell walls of bacteria, especiallyGram-positive bacteria likeBacillus andStreptococcus.

Lysozyme was the secondprotein structure, and the first enzyme structure, solved byX-ray diffraction methods. It was the first enzyme to be fullysequenced that contains all twenty commonamino acids.^[3]It was also the first enzyme to have a detailed, specific mechanism suggested for its action.^[4][5][6] This work led to an explanation of howenzymes speed up a chemical reaction by their physical structures.^[7]

• Host defence peptide
• Defensin
• innate immune system

• Enzymes
• Immunology

• CS1 maint: multiple names: authors list