Characterization, bioinformatic analysis and dithiocarbamate inhibition studies of two new α-carbonic anhydrases, CAH1 and CAH2, from the fruit fly Drosophila melanogaster.

Carbonic anhydrases (CAs) are essential and ubiquitous enzymes. Thus far, there are no articles on characterization of Drosophila melanogaster α-CAs. Data from invertebrate CA studies may provide opportunities for anti-parasitic drug development because α-CAs are found in many parasite or parasite vector invertebrates. We have expressed and purified D. melanogaster CAH1 and CAH2 as proteins of molecular weights 30kDa and 28kDa. CAH1 is cytoplasmic whereas CAH2 is a membrane-attached protein. Both are highly active enzymes for the CO2 hydration reaction, being efficiently inhibited by acetazolamide. CAH2 in the eye of D. melanogaster may provide a new animal model for CA-related eye diseases. A series of dithiocarbamates were also screened as inhibitors of these enzymes, with some representatives showing inhibition in the low nanomolar range.

The alpha and beta classes carbonic anhydrases from Helicobacter pylori as novel drug targets.

Helicobacter pylori (H. pylori) successfully resides in the human stomach in highly acidic conditions, causing a variety of gastroduodenal lesions, including gastric ulcer, gastric cancer and MALT lymphoma. For acid acclimation of H. pylori, two types of enzymes, urease and carbonic anhydrase (CA), play a central role. They cooperatively function to maintain neutral pH in the bacterial cytoplasm and periplasm. The genome project of H. pylori identified two different classes of CA with different subcellular localization: a periplasmic alpha-class CA (hp alphaCA) and a cytoplasmic beta-class CA (hp betaCA). These two CAs are catalytically efficient with almost identical activity to that of the human isoform CA I for the CO(2) hydration reaction, and highly inhibited by many sulfonamides/sulfamates, including acetazolamide, ethoxzolamide, topiramate and sulpiride, all clinically used drugs. Furthermore, certain CA inhibitors, such as acetazolamide and methazolamide, were shown to inhibit the bacterial growth in vitro. Since the efficacy of eradication therapies currently employed has been decreasing due to drug resistance and side effects of the commonly used drugs, the dual inhibition of alpha- and/or beta-CAs of H. pylori could be applied as an alternative therapy in patients with H. pylori infection or for the prevention of gastroduodenal diseases provoked by this widespread pathogen.