Disclosed is an isolated polypeptide comprising (a) the amino acid sequence of SEQ ID NO: 1 (b) a variant thereof having at least 95% identity to the amino acid sequence of SEQ ID NO: 1 over at least 810 contiguous amino acids of SEQ ID NO: 1 and having the endoglycosidase activity of a polypeptide consisting of the amino acid sequence of SEQ ID NO: 1. Also disclosed is an isolated polypeptide capable of binding to IgG and which does not have endoglycosidase activity comprising (a) the amino acid sequence of SEQ ID NO: 2 (b) a variant thereof having at least 95% identity to the amino acid sequence of SEQ ID NO: 1 over at least 810 contiguous amino acids of SEQ ID NO: 1, in which the amino acid equivalent to glutamic acid at position 186 is substituted.
