Fig. 2.

The temperature dependence of the enzyme activity. The activity at 75 °C was taken as 100%. Reactions were conducted in a temperature range from 36 to 92 °C in 0.05 mL of 20 mM Tris-HCl buffer, pH 8.0, containing: 1) 0.4 mM ATP, 1 mM ribose, 1 mM KH₂PO₄, 5 mM MgCl₂, 50 mM KCl, 0.15 μg of TspRK, 2) 1 mM ATP, 1 mM D-ribose 5-phosphate, 5 mM MgCl₂, 10 mM KH₂PO₄, 0.75 μg of TthPRPPS1 or TthPRPPS2, 3) 1 mM adenine, 1 mM PRPP, 5 mM MgCl₂, 0.125 μg of TthAPRT.