May serve as a plug to restrain the highly pressurized packaged genome and thus would be the first virion protein to contact the host cell wall, degrading the peptidoglycan layer and thereby facilitating viral genome entry into the host bacteria. Acts probably as a multifunctional enzyme that degrades N-acetylglucosamine polymers (in vitro) and cleaves the peptide cross-links of the host cell wall. Essential for the tail assembly. Binds 1 zinc ion per subunit. Located at the distal tip of the tail knob. In the N-terminal section; belongs to the glycosyl hydrolase 24 family. In the C-terminal section; belongs to the peptidase M23B family.