[Preparation and characteristics of carboxymethylated lysozyme derivatives]

Hen egg-white lysozyme (EC 3.2.1.17) was carboxymethylated with iodoacetic acid and the individual products of various degree of modification were isolated by column chromatography on Amberlite CG-50. Peptide mapping of the products obtained reveals that His-15, Lys-1, -33, -96 (or -97) residues are blocked; the Lys-13 and -116 residues are unmodified. Salt activation of the carboxymethylated derivatives is facilitated with the increase of the number of modified groups; this fact is consistent with the increased lytic activity and affinity to substrate of the derivatives at lowered ionic strength.