protein-coding gene in the species Homo sapiens

A lysozyme is a part of the innate immune system.[1] They are enzymes which are in mucus secretions like saliva. They protect against infection by chopping up the bacteria, viruses and fungi which infect animals.

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

Lysozyme is in a number of secretions, such as tears, saliva, milk, and mucus. It is also present in cytoplasmic granules of macrophages and granulocyte neutrophils.

The enzyme works by attacking polymers in the cell walls of bacteria, especially Gram-positive bacteria like Bacillus and Streptococcus.

Lysozyme was the second protein structure, and the first enzyme structure, solved by X-ray diffraction methods. It was the first enzyme to be fully sequenced that contains all twenty common amino 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 how enzymes speed up a chemical reaction by their physical structures.[7]



  1. Innate immune systems give immediate defence against infection, and are found in all plant and animal life.Janeway, Charles A. 2001. Evolution of the innate immune system. In Janeway, Charles; Paul Travers, Mark Walport, and Mark Shlomchik. Immunobiology, p598. 5th ed, New York and London: Garland Science. ISBN 978-0-8153-4101-7
  2. 2.0 2.1 Fleming A (1922). "On a remarkable bacteriolytic element found in tissues and secretions". Proceedings of the Royal Society B. 93 (653): 306–317. Bibcode:1922RSPSB..93..306F. doi:10.1098/rspb.1922.0023. JSTOR 80959.
  3. Canfield R.E (1963). "The amino acid sequence of egg white lysozyme". J Biol Chem. 238 (8): 2698–2707. doi:10.1016/S0021-9258(18)67888-3. PMID 14063294.
  4. Vernon C.A (1967). "The mechanisms of hydrolysis of glycosides and their relevance to enzyme-catalysed reactions". Proceedings of the Royal Society B. 167 (1009): 389–401. Bibcode:1967RSPSB.167..389V. doi:10.1098/rspb.1967.0036. JSTOR 75680. PMID 4382802.
  5. Rupley J.A (1967). "The binding and cleavage by Lysozyme of N-acetylglucosamine oligosaccharides". Proceedings of the Royal Society B. 167 (1009): 416–428. Bibcode:1967RSPSB.167..416R. doi:10.1098/rspb.1967.0038. JSTOR 75682. PMID 4382804. S2CID 33906706.
  6. Sharon N (1967). "The chemical structure of lysozyme substrates and their cleavage by the enzyme". Proceedings of the Royal Society B. 167 (1009): 402–415. Bibcode:1967RSPSB.167..402S. doi:10.1098/rspb.1967.0037. JSTOR 75681. PMID 4382803. S2CID 31794497.
  7. Vocadlo D.J, Davies G.J, Laine R, Withers S.G. (2001). "Catalysis by hen egg-white lysozyme proceeds via a covalent intermediate" (PDF). Nature. 412 (6849): 835–8. Bibcode:2001Natur.412..835V. doi:10.1038/35090602. PMID 11518970. S2CID 205020153.{{cite journal}}: CS1 maint: multiple names: authors list (link)