Studies of the Physicochemical and Enzymatic Properties of Papaya Lysozyme

Papaya lysozyme, purified by ion exchange chromatography on IRC-50, has been investigated with respect to physicochemical and enzymatic properties. In agreement with earlier findings, it was found that papaya lysozyme has a molecular weight of about 25,000 and that glycine is its sole amino-terminal residue. Molecular weight determinations in dissociating solvents indicate that the molecule consists of a single polypeptide chain. Papaya lysozyme lyses Micrococcus lysodeikticus cell walls at a rate one-third of that exhibited by egg white lysozyme; however, it displays a chitinase activity toward tetra-N-acetyl-d-glucosamine 400 times that of the egg white enzyme. No involvement of tryptophan residues in the active site of papaya lysozyme could be demonstrated.