FIGURE 5.

Activity testing of truncation mutants. Truncation mutant comprising the HexTF (A) and the SiaTF with variant N-terminal extensions (B–E) were assayed in the presence of both donor sugars and a suited fluorescently labeled acceptor as indicated. Reaction samples were taken after 15 s and 30 min. Peaks marked in gray represent 4-MU-DP1. These peaks are unchanged over the reaction course. A, NmW-(CΔ639)-His₆ with 4-MU-DP3 catalyzes the transfer of UDP-Gal by creating 4-MU-DP4. B, NmW-(NΔ398)-His₆ primed with 4-MU-DP2 catalyzes the transfer of CMP-Sia by producing 4-MU-DP3. C, NmW-(NΔ562)-His₆ primed with 4-MU-DP2 catalyzes the transfer of CMP-Sia by creating 4-MU-DP3. D, NmW-(NΔ609)-His₆ primed with 4-MU-DP2 catalyzes the transfer of CMP-Sia by producing 4-MU-DP3. E, NmW-(NΔ777)-His₆ primed with 4-MU-DP2 does not catalyze the transfer of CMP-Sia.