Comparison of α2,6-sialyltransferases for sialylation of therapeutic proteins.

The development of therapeutic proteins for the treatment of numerous diseases is one of the fastest growing areas of biotechnology. Therapeutic efficacy and serum half-life are particularly important, and these properties rely heavily on the glycosylation state of the protein. Expression systems to produce authentically fully glycosylated therapeutic proteins with appropriate terminal sialic acids are not yet perfected. The in vitro modification of therapeutic proteins by recombinant sialyltransferases offers a promising and elegant strategy to overcome this problem. Thus, the detailed expression and characterization of sialyltransferases for completion of the glycan chains is of great interest to the community. We identified a novel α2,6-sialyltransferase from Helicobacter cetorum and compared it to the human ST6Gal1 and a Photobacterium sp. sialyltransferase using glycoprotein substrates in a 96-well microtiter-plate-based assay. We demonstrated that the recombinant α2,6-sialyltransferase from H. cetorum is an excellent catalyst for modification of N-linked glycans of different therapeutic proteins.