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

摘要

Burkholderia territorii , a Gram-negative bacterium, encodes for the ι-class carbonic anhydrase (CA, EC 4.2.1.1) BteCAι, which was recently characterised. It acts as a good catalyst for the hydration of CO 2 to bicarbonate and protons, with a k cat value of 3.0?×?10 5 ?s ?1 and k cat /K M value of 3.9?×?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 BteCAι, which we prove to be a zinc(II)- and not manganese(II)-containing enzyme, as reported for diatom ι-CAs. The best inhibitors were sulphamic acid, stannate, phenylarsonic acid, phenylboronic acid and sulfamide (K I values of 6.2–94?μM), 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.