Turkey egg white lysozyme. Preparation of the crystalline enzyme and investigation of the amino acid sequence.

Crystalline turkey egg white lysozyme has been prepared by a simple procedure consisting of adsorption on carboxymethylcellulose followed by elution with (NH4)&03 solution and crystallization from 5 % NaCl solution. The twice crystallized enzyme gave a single peak when eluted from carboxymethylcellulose, and it migrated as a single band during disc electrophoresis. Separation of the tryptic peptides from reduced and S-carboxymethylated turkey egg white lysozyme has yielded peptides analogous to those of reduced and S-carboxymethylated chicken egg white lysozyme. It is found that the turkey enzyme amino acid sequence differs from that of the chicken lysozyme at a minimum of seven positions which are distributed over six of these tryptic peptides. The replacements detected from examination of these peptides are: Tyr for Phe3, Leu for HisIS, His for Glnll, Lys for Arg,,, Ala for Val,,, Gly for AsplO,, and His for Glnlzl of the chicken egg white lysozyme. The apparent occurrence of glycine as Residue 101 of turkey egg white lysozyme is especially interesting inasmuch as the x-ray crystallographic investigation of chicken egg white lysozyme and its complexes with certain inhibitors has led to the view that the carboxyl group of Asplo is involved in binding substrates.