Immunochemical Studies on Hen's Egg-White Lysozyme.

By selective nitration of egg-white lysozyme it is possible to obtain five lysozyme derivatives. Nitration of tyrosine 20 or tyrosine 23 slightly lowers the enzymatic activity and the thermal stability of the protein, modification of tyrosine 53 has a more drastic effect. Lysozyme nitrated on tyrosine 20 or tyrosine 23 loses one antigemc site. These two residues appear to belong to the same antigenic determinant, as lysozyme nitrated on these two tyrosines reacts with the same antibodies than the two former derivatives. Tyrosine 53 belongs to a second antigenic determinant of the enzyme, as it appears from the reaction between trinitrated lysozyme and the antilysozyme antibodies. [ABSTRACT FROM AUTHOR]