Bacteriophage T4, Gp5, tail-associated lysozyme <p>O-Glycosyl hydrolases <db_xref db="EC" dbkey="3.2.1."/> are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycosyl hydrolases, based on sequence similarity, has led to the definition of 85 different families [<cite idref="PUB00004870"/>, <cite idref="PUB00005266"/>]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site.</p><p>Glycoside hydrolase family 24 <db_xref db="CAZY" dbkey="GH24"/> comprises enzymes with only one known activity; lysozyme (<db_xref db="EC" dbkey="3.2.1.17"/>). This family includes lambda phage lysozyme. </p><p>T4 lysozyme helps to release mature phage particles from the cell wall bybreaking down the peptidoglycan. The enzyme hydrolyses the 1,4-betalinkages between N-acetyl-D-glucosamine and N-acetylmuramic acid inpeptidoglycan heteropolymers of prokaryotic cell walls.</p><p>The T4 lysozyme structure contains 2 domains, the interface between whichforms the active-site cleft. The N terminus of the 2 domains undergoes a'hinge-bending' motion about an axis passing through the molecular waist[<cite idref="PUB00004082"/>]. This mobility is thought to be important in allowing access ofsubstrates to the enzyme active site.</p>