(a) GST-NEU2 (1.13 mU) was incubated with Neu5Acα2-3Lac in buffer containing 200 mM sodium phosphate, 100 mM sodium acetate, 100 mM NaCl at the indicated pH, for 1 h at 37 °C. Error bars represent standard deviation of three trials. (b) GST-NEU2 activity (1.13 mU) was measured in 100 mM NaOAc, pH 5.6, 100 mM NaCl at 37 °C for 1 h. Buffer was varied by presence of 1 mM CaCl2, MgCl2, EDTA, zanamivir, DANA, or oseltamivir, as indicated. Error bars represent standard deviation of three trials.