Effect of amino acids and amines on the activity of the recombinant ι-carbonic anhydrase from the Gram-negative bacterium Burkholderia territorii

We here report a study on the activation of the iota-class bacterial CA from Burkholderia territorii (BteCA iota). This protein was recently characterised as a zinc-dependent enzyme that shows a significant catalytic activity (k (cat) 3.0 x 10(5) s(-1)) for the physiological reaction of CO2 hydration to bicarbonate and protons. Some amino acids and amines, among which some proteinogenic derivatives as well as histamine, dopamine and serotonin, showed efficient activating properties towards BteCA iota, with activation constants in the range 3.9-13.3 mu M. L-Phe, L-Asn, L-Glu, and some pyridyl-alkylamines, showed a weaker activating effect towards BteCA iota, with K-A values ranging between 18.4 mu M and 45.6 mu M. Nowadays, no information is available on active site architecture, metal ion coordination and catalytic mechanism of members of the iota-group of CAs, and this study represents another contribution towards a better understanding of this still uncharacterised class of enzymes.