PROCESS FOR THE MODIFICATION OF A GLYCOPROTEIN USING A GLYCOSYLTRANSFERASE THAT IS OR IS DERIVED FROM A BETA-(1,4)-N-ACETYLGALACTOSAMINYLTRANSFERASE

The present invention relates to a process for the enzymatic modification of a glycoprotein. The process comprises the step of contacting a glycoprotein comprising a glycan comprising a terminal GlcNAc-moiety, in the presence of glycosyltransferase that is, or is derived from, a ²-(1,4)-N-acetylgalactosaminyltransferase, with a non-natural sugar-derivative nucleotide. The non-natural sugar-derivative nucleotide is according to formula (3): wherein A is selected from the group consisting of -N 3 , -C(O)R 3 , -(CH 2 ) i C‰¡C-R 4 , -SH, -SC(O)R 8 , -SC(O)OR 8 , -SC(S)OR 8 , -F, -Cl, -Br -I, -OS(O) 2 R 5 , terminal C 2 - C 24 alkenyl groups, C 3 - C 5 cycloalkenyl groups, C 4 - C 8 alkadienyl groups, terminal C 3 - C 24 allenyl groups and amino groups. The invention further relates to a glycoprotein obtainable by the process according to the invention, to a bioconjugate that can be obtained by conjugating the glycoprotein with a linker-conjugate, and to ²-(1,4)-N-acetylgalactosaminyltransferases that can be used in preparing the the glycoprotein according to the invention.