What is "lysin"

n. any substance or antibody that can cause the destruction (by lysis) of blood cells, bacteria etc

n. any substance (such as an antibody) or agent that can cause lysis

Lysins, also known as endolysins or murein hydrolases, are hydrolytic enzymes produced by bacteriophages in order to cleave the host's cell wall during the final stage of the lytic cycle. Lysins are highly evolved enzymes that are able to target one of the five bonds in peptidoglycan (murein), the main component of bacterial cell walls, which allows the release of progeny virions from the lysed cell. These enzymes are being used as antibacterial agents due to their high effectiveness and specificity in comparison with antibiotics, which are susceptible to bacterial resistance.

Not all bacteriophages synthesize lysins, some small single-stranded DNA and RNA phages produce membrane proteins that activate the host's autolytic mechanisms.

The term lysin may refer to any protein that causes cell lysis, such as:

• Most commonly, phage lysins, also known as endolysins
• Autolysin
• Cytolysin
• Egg lysin
• Hemolysin
• NK-lysin
• Streptolysin