Novel polypeptide and its use having epimerase activity

Enzymes that produce oligosaccharides with beta-l, 4 bonds, a method of manufacturing the oligosaccharide, and to provide a functional food based on the new functions of the oligosaccharide. A polypeptide consisting of the amino acid sequence of any one of (A) ~ (C), provides a polypeptide characterized by having epimerase activity against oligosaccharide having at least beta-l, 4 bonds: (A) the amino acid sequence shown in SEQ ID NO: 1; (B) 1 one or several amino acids in the amino acid sequence shown in SEQ ID NO: 1 is substituted, added or have been deleted, the amino acid sequence; or (C) SEQ ID NO: 1 with an amino acid sequence at least 51% indicated amino acid sequence homology. The present invention provides a functional food characterized by containing a 4-O-β-D- galactopyranosyl -D- mannose.