The mechanism by which lysozyme catalyzes the cleavage of the glycosidic bonds of peptidoglycan involves donation of a proton by one of its glutamic acid residues to the oxygen atom of the glycosidic bond, which leads to acid cleavage of the ether linkage. The resulting carbocation is stabilized by resonance that is possible only because the sugar ring has been distorted by the active site into a half-chair conformation.