Kinetic and anion inhibition studies of a beta-carbonic anhydrase (FbiCA 1) from the C-4 plant Flaveria bidentis

Several beta-carbonic anhydrases (CAs, EC 4.2.1.1) are present in all land plants examined thus far. Here we report the first detailed biochemical characterization of one such isoform, FbiCA 1, from the C-4 plant Flaveria bidentis, which was cloned, purified and characterized as recombinant protein. FbiCA 1 has an interesting CO2 hydrase catalytic activity (k(cat) of 1.2 x 10(5) and k(cat)/K-m of 7.5 x 10(6) M-1 x s(-1)) and was moderately inhibited by most simple/complex inorganic anions. Potent FbiCA 1 inhibitors were also detected, such as trithiocarbonate, diethyldithiocarbamate, sulfamide, sulfamic acid, phenylboronic acid and phenylarsonic acid (K(I)s in the range of 4-60 mu M). Such inhibitors may be used as tools to better understand the role of various beta-CA isoforms in photosynthesis.