What does lysozyme mean?
Lysozyme is an enzyme, or biological catalyst, that helps break down the peptidoglycan surrounding bacterial cells. By damaging this rigid cell-wall structure, it can cause susceptible bacteria to rupture and die. The enzyme is naturally present in human tears, saliva, nasal secretions, and other fluids, as well as in materials such as egg white, where it forms part of an ancient non-specific defence against infection. Lysozyme also has specialised laboratory and industrial uses: researchers may use it to disrupt bacterial cell walls and extract their contents, and food scientists study its antimicrobial activity. Although the word can be used more broadly for enzymes associated with cellular breakdown, its dominant modern meaning refers to the antibacterial enzyme also known as muramidase. Its importance lies in its simple mechanism and wide distribution across animal tissues and secretions.
nounAn enzyme that breaks down the peptidoglycan cell walls of bacteria, causing them to rupture. It occurs naturally in tears, saliva, mucus, egg white, and many other biological materials.
- A naturally occurring enzyme that hydrolyses peptidoglycan in bacterial cell walls and can therefore destroy or inhibit susceptible bacteria.
- Any of a broader class of enzymes associated with cellular lysis or breakdown, particularly enzymes used experimentally to disrupt cells.
"The scientist measured lysozyme activity in the patient's tears to assess the strength of the body's natural defences."
"The laboratory added lysozyme to isolate the bacterial contents without rupturing the cell membrane."
"Lysozyme is abundant in tears, saliva, and other secretions that form part of the body's innate immune defences."
The plural is grammatically correct but is rarely needed in ordinary writing, since the word usually occurs in the singular in discussions of the enzyme.
"The researchers compared the effects of two lysozymes isolated from different sources."
A single drop of tear can contain enough lysozyme to help tear apart a bacterium—tears are not merely emotional signalling fluids, but part of the body's chemical defence system.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does lysozyme come from?
The word was coined in the early 20th century by the Scottish bacteriologist Alexander Fleming for the substance he found in egg white that destroyed bacteria. It combines Greek lysis, meaning dissolution or breakdown, with the suffix -zyme, derived from Greek zyme, meaning leaven or ferment, both ultimately associated with the action of enzymes. Its formation reflects Fleming's observation that bacterial cells could be dissolved rather than merely stopped in their growth.
How lysozyme is actually used
The word is primarily used in biology, medicine, biochemistry, and food science. In general writing, it usually refers specifically to the antibacterial enzyme that hydrolyses bacterial peptidoglycan; it is also used in laboratory procedures for breaking down bacterial cell walls.
Easily confused with lysozyme
Lysozyme is an enzyme that can break down bacterial cell walls, whereas a lysosome is a membrane-bound cell structure that contains digestive enzymes.