Figure 8.

RoGalU2 enzyme activity depending on the buffer (a) and pH (b) of the reaction solution. (a) Assay mixtures contained 1.5 mM UTP, 250 mM glucose 1-phosphate, 1 mM MgCl₂, 50 mM buffer, pH 7.4, 1.7 µg RoGalU2. Reaction was carried out at 42 °C in 1 mL volume. (b) Assay mixtures contained 1.5 mM UTP, 250 mM glucose 1-phosphate, 1 mM MgCl₂, 50 mM Imidazole, pH 6.6–7.4 (black triangle) or 50 mM Hepes, pH 7.4–8.4 (black circle) or 50 mM Tris-HCl, pH 7.6–9.3 (white circle), 1.7 µg RoGalU2. Reaction was carried out at 42 °C in 1 mL volume. Means with standard deviations are shown out of a minimum set of three independent measurements. 100% relative activities correspond to 126 U mg⁻¹ (a) and 109 U mg⁻¹ (b).