The surface functional properties of glycosylated lysozyme were investigated by using polymannosyl and oligomannosyl enzymes at the position 49 by genetic modification [Nakamura S. et al. (1993) J. Biol. Chem. 268, in press]. The polymannosyl lysozyme exhibited excellent emulsifying properties superior to those of commercial emulsifiers in addition to heat stability, while the oligomannosyl lysozyme did not. The surface tension of the polymannosyl lysozyme was greatly decreased correspondingly to the enhanced emulsifying properties, although that of oligomannosyl protein was not. The emulsifying activity and the emulsion stability of the polymannosyl lysozyme were stable in acidic pH or high salt conditions; in addition, they were greatly enhanced also by preheating the polymannosyl lysozyme. Thus novel surface functional properties of polymannosyi lysozyme in addition to heat stability suggest the direction of the design of new functional proteins by genetic modification.
