lytic transglycosylase-like domain of tail fiber-like proteins and similar domains. These tail fiber-like proteins are multi-domain proteins that include a lytic transglycosylase (LT) domain. Members of the LT family include the soluble and insoluble membrane-bound LTs in bacteria, the LTs in bacteriophage lambda, and the eukaryotic "goose-type" lysozymes (goose egg-white lysozyme; GEWL). LTs catalyze the cleavage of the beta-1,4-glycosidic bond between N-acetylmuramic acid (MurNAc) and N-acetyl-D-glucosamine (GlcNAc), as do "goose-type" lysozymes. However, in addition to this, they also make a new glycosidic bond with the C6 hydroxyl group of the same muramic acid residue.

SLT domain protein [Mobilome: prophages, transposons].

Peptidase family M23. Members of this family are zinc metallopeptidases with a range of specificities. The peptidase family M23 is included in this family, these are Gly-Gly endopeptidases. Peptidase family M23 are also endopeptidases. This family also includes some bacterial lipoproteins for which no proteolytic activity has been demonstrated. This family also includes leukocyte cell-derived chemotaxin 2 (LECT2) proteins. LECT2 is a liver-specific protein which is thought to be linked to hepatocyte growth although the exact function of this protein is unknown.

M23 family metallopeptidase, also known as beta-lytic metallopeptidase, and similar proteins. This model describes the metallopeptidase M23 family, which includes beta-lytic metallopeptidase and lysostaphin. Members of this family are zinc endopeptidases that lyse bacterial cell wall peptidoglycans; they cleave either the N-acylmuramoyl-Ala bond between the cell wall peptidoglycan and the cross-linking peptide (e.g. beta-lytic endopeptidase) or a bond within the cross-linking peptide (e.g. stapholysin, and lysostaphin). Beta-lytic metallopeptidase, formerly known as beta-lytic protease, has a preference for cleavage of Gly-X bonds and favors hydrophobic or apolar residues on either side. It inhibits growth of sensitive organisms and may potentially serve as an antimicrobial agent. Lysostaphin, produced by Staphylococcus genus, cleaves pentaglycine cross-bridges of cell wall peptidoglycan, acting as autolysins to maintain cell wall metabolism or as toxins and weapons against competing strains. Staphylolysin (also known as LasA) is implicated in a range of processes related to Pseudomonas virulence, including stimulating shedding of the ectodomain of cell surface heparan sulphate proteoglycan syndecan-1, and elastin degradation in connective tissue. Its active site is less constricted and contains a five-coordinate zinc ion with trigonal bipyramidal geometry and two metal-bound water molecules, possibly contributing to its activity against a wider range of substrates than those used by related lytic enzymes, consistent with its multiple roles in Pseudomonas virulence. The family includes members that do not appear to have the conserved zinc-binding site and might be lipoproteins lacking proteolytic activity.

Phage-related tail protein [Mobilome: prophages, transposons].