Regulation of Chloroplastic Carbonic Anhydrase

Abstract
It was previously reported that Mg ion inhibited carbonic anhydrase. Studies with partially purified carbonic anhydrase from spinach (Spinacia oleracea L.) chloroplasts show that the effect was the result of the chloride counterion and not the Mg ion. Enzyme activity was reduced 50% upon addition of 3-10 mM MgCl2 or KCl, while all additions of MgSO4 between 0.3-10 mM were mildly stimulatory.