PROCESS FOR THE MONO- AND BI-SIALYLATION OF GLYCOPROTEINS EMPLOYING N-TERMINALLY TRUNCATED BETA-GALACTOSIDE ALPHA-2,6-SIALYLTRANSFERASE MUTANTS

摘要

The present disclosure is directed to the use of certain glycosyltransferase variants having N-terminal truncation deletions. It was found that the combination of two different truncation variants of human ß-galactoside-a-2,6-sialyltransferase I (hST6Gal-I) exhibited different specific sialyltransferase enzymatic activities. In one example, under conditions wherein the first variant ?89 hST6Gal-I catalyzed formation of bi-sialylated target molecules the second variant ?108 hST6Gal-I catalyzed formation of mono-sialylated target molecules. Thus, disclosed are variants of mammalian glycosyltransferase, nucleic acids encoding the same, methods and means for recombinantly producing the variants of mammalian glycosyltransferase and use thereof, particularly for sialylating in a quantitatively controlled manner terminal acceptor groups of glycan moieties being part of glycoproteins such as immunoglobulins.