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. Author manuscript; available in PMC: 2026 Sep 1.
Published in final edited form as: Carbohydr Res. 2026 Jun 26;567:110019. doi: 10.1016/j.carres.2026.110019

Fig. 4.

Fig. 4.

Comparative analysis of enzymatic sialylation of antibodies by the bacterial sialyltransferases. A) Time course profile of sialylation of LacdiNAc-trastuzumab (3) catalyzed by Pd2,6ST (n = 1). B) Time course profile of sialylation of 3 catalyzed by PmST1 M144D (n = 1). C) Comparison of Pd2,6ST catalyzed sialylation of G2-trastuzumab glycoform (1) and G2-F241A trastuzumab (6) (n = 1). D) Comparison of PmST1 M144D catalyzed sialylation of 1 and 6 (n = 1). Enzymatic reaction conditions: A mixture of the LacdiNAc-trastuzumab (3), the G2-trastuzumab (1), or the G2-F241A trastuzumab (6) (30 mg/ml), and CMP-Neu5Ac (150 eq) in a Tris buffer (100 mM, pH 7.5) was incubated with Pd2,6ST or PmST1 M144D (0.2 mg/ml) at 37 °C. The reactions were monitored by LC-MS analysis of the Fc fragment released by IdeS treatment of the antibodies. The reaction yield was calculated as the sum of the disialylated product yield and one-half of monosialylated product yield.