The invention provides an endoglycosidase, referred to as EndoS49 and having the amino acid sequence of SEQ ID NO: 1. EndoS49 was isolated from Streptococcus pyogenes strain NZ131 and is a homolog of EndoS. EndoS49 has specific endoglycosidase activity on native IgG and cleaves a larger variety of Fc glycans than EndoS. A mutant thereof where the glutamic acid at position 186 of SEQ ID NO: 1 was substituted was produced: said mutant lacks endoglycosidase activity but is capable of binding to IgG. Methods using EndoS49, deletions thereof and said mutant, especially for assessing glycosylation of IgG or for isolating IgG are disclosed.
