Studies on mechanisms of bacterial infection and protection in fish. II. Enzymatic properties of partially purified lysozyme from the skin mucus of carp.

The lysozyme was partially purified from the skin mucus of carp Cyprinus carpio by chitin coated cellulose and carboxymethyl cellulose and examined for the enzymatic properties. On the electrophoretic analysis, the partially purified lysozyme appeared in two bands in SDS-polyacrylamide gel and the molecular weight of each was 24, 000 and 33, 000. The partially purified lysozyme showed the maximum activity of the lysis of Micrococcus lysodeikticus at 40°C in 0.01M phosphate buffer. The pH optima of this fraction were 7.2 in 0.01M phosphate buffer and 9.0 in glycine-NaOH buffer. The lysozyme of carp skin mucus heated at 100°C for 10 min in the acidic buffer (pH 3.5) was relatively stable but that in the neutral (pH 7.0) or the alkaline (pH 9.0) buffer was liable to be inactivated, as shown by the lysozyme from the hen egg-white.