A mutant of EndoS2 includes one or more mutations in the sequence of a wild-type EndoS2 (SEQ ID NO: 1), wherein the one or more mutations are in a peptide region located within residues 133-143, residues 177-182, residues 184-189, residues 221-231, and/or residues 227-237, wherein the mutant of EndoS2 has a low hydrolyzing activity and a high tranglycosylation activity, as compared to those of the wild-type EndoS2. A method for preparing an engineered glycoprotein using the mutant of EndoS2 includes coupling an activated oligosaccharide to a glycoprotein acceptor. The activated oligosaccharide is a glycan oxazoline.

Methods are provided for making bispecific antibodies and antibody conjugates comprising site-specifically cross-linking two or more antibodies, antibody fragments or Fc-fusion proteins. Also provided are compositions and uses for the bispecific antibodies and antibody conjugates. The bispecific antibodies may be used to treat a disease or condition. Also provided are methods for site-specifically conjugating a liposome, an mRNA or an siRNA to an antibody, and uses of the antibody-conjugated liposome, mRNA or siRNA.

The present disclosure provides a one-pot chemoenzymatic method for site-specific modification and conjugation of antibodies at their Fc glycan site to produce structurally well-defined antibody conjugates carrying defined drugs and other entities. The method is enabled by the discovery that certain endoglycosidases have the ability to both deglycosylate an antibody and to recognize selectively modified small disaccharide oxazolines for transglycosylation on antibodies without hydrolysis of the resulting products.

Methods for producing virus particles and viral antigens with simplified glycosylation profiles, such as mono-glycosylated forms of HIV, HCV, Dengue virus, West Nile virus and influenza virus. When used as targets for vaccine production, the conserved nature of such sites generate vaccines that are less sensitive to viral mutations. Such methods may include the use of glycosylation inhibitors for production of viruses or viral antigens with simplified glycosylation profiles.

Methods and compositions related to high mannose glycans are described.

A mutant of EndoS2 includes one or more mutations in the sequence of a wild-type EndoS2 (SEQ ID NO: 1), wherein the one or more mutations are in a peptide region located within residues 133-143, residues 177-182, residues 184-189, residues 221-231, and/or residues 227-237, wherein the mutant of EndoS2 has a low hydrolyzing activity and a high tranglycosylation activity, as compared to those of the wild-type EndoS2. A method for preparing an engineered glycoprotein using the mutant of EndoS2 includes coupling an activated oligosaccharide to a glycoprotein acceptor. The activated oligosaccharide is a glycan oxazoline.

Provided in certain embodiments are new methods for forming azido modified biomolecule conjugates of reporter molecules, carrier molecules or solid support. In other embodiments are provided methods for enzymatically labeling a biomolecules with an azide group.

The present invention provides for recombinant Endo-S mutants that exhibit reduced hydrolysis activity and increased transglycosylation activity for the synthesis of glycoproteins wherein a desired sialylated oxazoline or synthetic oligosaccharide oxazoline is added to a core fucosylated or nonfucosylated GlcNAc-protein acceptor. Such recombinant Endo-S mutants are useful for efficient glycosylation remodeling of IgG1-Fc domain to provide different antibody glycoforms carrying structurally well-defined Fc N-glycans.

The invention relates to a method for improving the benefit of a therapy or a therapeutic agent to a subject. The method comprises administering to the subject an agent which reduces Fc receptor binding of serum IgG molecules in the subject; and subsequently administering said therapy or said therapeutic agent to the subject. The invention also relates to a method for reducing the effect of pathogenic autoantibodies in a subject, the method comprising (a) administering to the subject an agent which reduces Fc receptor binding of serum IgG molecules in the subject and optionally (b) subsequently subjecting the subject to a treatment which removes endogenous autoantibodies. The invention also relates to a kit for carrying out a method of the invention.

The present disclosure relates to a novel mutant form of -fucosidase (-L-fucosidase), which exhibits enhanced -(1,6) fucosidase activity. The present disclosure also relates to the compositions comprising the novel mutant form of -fucosidase, and the methods of using the novel mutant form of -fucosidase to cleave -(1,6)-linked fucoses in the glycoconjugates.