Kawamura S, Toshima G, Imoto T, Araki T, Torikata T. Amino Acid Residues in Subsites E and F Responsible for the Characteristic Enzymatic Activity of Duck Egg-White Lysozyme. Journal of Biochemistry. 2002 May 01;131(5):663–70. doi: 10.1093/oxfordjournals.jbchem.a003149.