Figure 5.

Mutational effects on 2′,3′ cyclic phosphodiesterase activity. Reaction mixtures (25 µl) containing 50 mM Tris–HCl (pH 7.5), 0.5 mM MnCl₂, 5 mM 2′,3′ cAMP, 1 U CIP and 0.5 µg CthPnkp as specified were incubated for 30 min at 45°C. (A) Effects of alanine mutations. (B) Effects of conservative substitutions. Each datum in the bar graph is the average of two separate experiments. S.E. bars are shown.