Modified glycoprotein, protein-conjugate and process for the preparation thereof

A process for the preparation of a modified glycoprotein, comprising:

• contacting a glycoprotein comprising a GlcNAcMan5GlcNAc2 glycan with Su(A)x-P in the presence of a catalyst selected from the group consisting of β(1,4)-galactosyltransferases, N-galactosyltransferases, β(1,4)-galactosyltransferases comprising a mutant catalytic domain, and β(1,3)-N-galactosyltransferases comprising a mutant catalytic domain;
• wherein:
• the core GlcNAc residue of the glycan is optionally fucosylated;
• Su(A)x is a monosaccharide sugar derivative comprising x functional groups A, wherein x is 1, 2, 3 or 4 and A is independently selected from the group consisting of an azido group, a keto group, an alkynyl group, a thiol group or a precursor thereof, a halogen, a sulfonyloxy group, a halogenated acetamido group, a mercaptoacetamido group and a sulfonylated hydroxyacetamido group;
• P is a nucleotide;
• wherein the modified glycoprotein is a glycoprotein comprising a Su(A)xGlcNAcMan5GlcNAc2 glycan wherein the core GlcNAc residue is optionally fucosylated;
• and
• wherein GlcNAcMan5GlcNAc2 is a glycan according to formula (101) and Su(A)xGlcNAcMan5GlcNAc2 is a glycan according to formula (102):
• wherein b is 0 or 1 and Su(A)x is as defined above.