Fig. 4.

Effect of CO₂ on absorbance at 300 nm. (A) Conditions were as in Fig. 1. Reaction was started by addition of at the first arrow and 0.15 ml of ice water saturated with CO₂ added to the total volume of 3.0 ml at the second arrow. (B) Conditions were as in Fig. 1 except that was added to 10 mM. Line 1, added at the first arrow. Line 2, carbonic anhydrase (CA) was added to 50 μg/ml at the second arrow and CO₂ added at the third arrow. Line 3, CO₂ added at the first arrow and added at the second arrow.