The catalytic activity and the inhibition of a new coral carbonic anhydrase (CA, EC 18.104.22.168), from the scleractinian coral Stylophora pistillata, STPCA-2, has been investigated. STPCA-2 has high catalytic activity for the physiological reaction being less sensitive to anion and sulfonamide inhibitors compared to STPCA, a coral enzyme previously described. The best STPCA-2 anion inhibitors were sulfamide, sulfamic acid, phenylboronic acid, and phenylarsonic acid (K(I)s of 5.7-67.2μM) whereas the best sulfonamide inhibitors were acetazolamide and dichlorophenamide (K(I)s of 74-79nM). Because this discriminatory effect between these two coral CAs, sulfonamides may be useful to better understand the physiological role of STPCA and STPCA-2 in corals and biomineralization processes.
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