Anion inhibition studies of the Zn(II)-bound ι-carbonic anhydrase from the Gram-negative bacterium Burkholderia territorii

Burkholderia territorii, a Gram-negative bacterium, encodes for the iota-class carbonic anhydrase (CA, EC 4.2.1.1) BteCA iota, which was recently characterised. It acts as a good catalyst for the hydration of CO2 to bicarbonate and protons, with a k(cat) value of 3.0 x 10(5) s(-1) and k(cat)/K-M value of 3.9 x 10(7) M-1 s(-1). No inhibition data on this new class of enzymes are available to date. We report here an anion and small molecules inhibition study of BteCA iota, which we prove to be a zinc(II)- and not manganese(II)-containing enzyme, as reported for diatom iota-CAs. The best inhibitors were sulphamic acid, stannate, phenylarsonic acid, phenylboronic acid and sulfamide (K-I values of 6.2-94 mu M), whereas diethyldithiocarbamate, tellurate, selenate, bicarbonate and cyanate were submillimolar inhibitors (K-I values of 0.71-0.94 mM). The halides (except iodide), thiocyanate, nitrite, nitrate, carbonate, bisulphite, sulphate, hydrogensulfide, peroxydisulfate, selenocyanate, fluorosulfonate and trithiocarbonate showed K-I values in the range of 3.1-9.3 mM.

Automated summary

This study reported an anion and small molecules inhibition study of BteCA iota, proving it to be a zinc(II)-containing enzyme rather than manganese(II)-containing enzyme. The best inhibitors were found to be sulphamic acid, stannate, phenylarsonic acid, among others.