Two N-terminally truncated variants of human {beta}-galactoside {alpha}2,6 sialyltransferase I with distinct properties for in vitro protein glycosylation

We report on the distinct properties of two N-terminally truncated versions of ST6Gal-I, namely 89ST6Gal-I and 108ST6Gal-I, which were successfully expressed in human embryonic kidney cells. The different properties of these enzymes result most probably from the loss of interactions from helix α1 in the 108ST6Gal-I variant, which plays a role in acceptor substrate binding. The Km for N-acetyl-d-lactosamine was 10-fold increased for 108ST6Gal-I (84 mM) as compared to 89ST6Gal-I (8.3 mM). The two enzyme variants constitute a suitable tool box for the terminal modification of N-glycans. While the enzyme 89ST6Gal-I exhibited both ST (di-sialylation) and sialidase activity on a monoclonal antibody, the enzyme 108ST6Gal-I showed only ST activity with specificity for mono-sialylation.

Source: Glycobiology - October 18, 2016 Category: Biology Authors: Luley-Goedl, C., Schmoelzer, K., Thomann, M., Malik, S., Greif, M., Ribitsch, D., Jung, C., Sobek, H., Engel, A., Mueller, R., Schwab, H., Nidetzky, B. Tags: Glycan Synthesis Source Type: research