Carbonic anhydrase inhibitors. Inhibition of the β-class enzyme from the pathogenic yeast Candida glabrata with anions

A β-carbonic anhydrase (CA, EC 4.2.1.1), the protein encoded by the NCE103 gene of Candida glabrata which also present in Candida albicans and Saccharomycescerevisiae, was cloned, purified, characterized kinetically and investigated for its inhibition by a series simple, inorganic anions such as halogenides, pseudohalogenides, bicarbonate, carbonate, nitrate, nitrite, hydrogen sulfide, bisulfite, perchlorate, sulfate and some isosteric species. The enzyme showed significant CO2 hydrase activity, with a kcat of 3.8 × 105 s−1 and kcat/KM of 4.8 × 107 M−1 s−1. The Cà glabrata CA (CgCA) was moderately inhibited by metal poisons (cyanide, azide, cyanate, thiocyanate, KIs of 0.60–1.12 mM) but strongly inhibited by bicarbonate, nitrate, nitrite and phenylarsonic acid (KIs of 86–98 μM). The other anions investigated showed inhibition constants in the low millimolar range, with the exception of bromide and iodide (KIs of 27–42 mM).

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