Lysozyme in hen blood serum.

Hen blood serum (White Leghorn) possessed the lytic action against Micrococcus lysodeikticus which was less than one-thousandth of egg white obtained from hens of the same species, suggesting that lysozyme was present. The filter-sterilized hen blood serum also inhibited the growth of M. lysodeikticus in broth culture. The isolated lysozyme, purified by column chromatography and gel filtration, proved to be a basic protein with a low molecular weight (about 15,000), active against M. lysodeikticus, and more stable at acidic pH values than at alkaline pH values when heated. In amino acid composition, the isolated serum lysozyme had slightly higher proline and lower aspartic acid content than hen egg white lysozyme. The blood serum lysozyme was less heat stable at various pH values (4.5 to 8.4) than egg white lysozyme.