Endolysin is a generic term describing an enzyme that lyses a bacterial membrane.

At the end of the bacteriophage replication cycle, bacteriophages have to release their newly formed progeny. The major barrier to overcome is the peptidoglycan. To degrade this layer, bacteriophages contain endolysins.

Depending on the bond these enzymes cleave, we can distinguish muramidases (lysozyme), transglycosylases, amidases or endopeptidases.