Characterization of Maillard-type lysozyme-galactomannan conjugate having immune-enhancing effects

In the present study, lysozyme-galactomannan conjugate (LGC) was fractionated by ion-exchange chromatography, the immune activity of the fractions was confirmed, and a structural analysis of the glycoprotein was performed. A high-molecular-weight fraction of LGC (H-LGC), was characterized by using a method using matrix-assisted laser desorption/ionization time of flight mass spectrometry. The glycated site of H-LGC was determined to be the lysine (Lys)115 residue. In addition, about 1mol of galactomannan (G) was linked to 1mol of lysozyme (L) in LGC based on the binding weight ratio. Conjugation of L and G reduced the aggregation of particles, resulting in a monodispersion based on measurement of dynamic light scattering. LGC in solution showed heterogeneous shapes with a mean size of 337nm. Therefore, we suggest that LGC improves the immune-enhancing activity as G conjugates the site of Lys115 on L, and provides higher solubility with reduced aggregation for the industrial use of LGC as a food constituent.