Publications (49) View all
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Article: Anion inhibition studies of the α-carbonic anhydrase from the pathogenic bacterium Vibrio cholerae.
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ABSTRACT: An α-carbonic anhydrase (CA, EC 4.2.1.1) has been recently cloned and characterized in the human pathogenic bacterium Vibrio cholerae, denominated VchCA (Del Prete et al. J. Med. Chem.2012, 55, 10742). This enzyme shows a good catalytic activity for the CO hydration reaction, comparable to that of the human (h) isoform hCA I. Many inorganic anions and several small molecules were investigated as VchCA inhibitors. Inorganic anions such as cyanate, cyanide, hydrogen sulfide, hydrogen sulfite, and trithiocarbonate were effective VchCA inhibitors with inhibition constants in the range of 33-88μM. Other effective inhibitors were diethyldithiocarbamate, sulfamide, sulfamate, phenylboronic acid and phenylarsonic acid, with Ks of 7-43μM. Halides (bromide, iodide), bicarbonate and carbonate were much less effective VchCA inhibitors, with Ks in the range of 4.64-28.0mM. The resistance of VchCA to bicarbonate inhibition may represent an evolutionary adaptation of this enzyme to living in an environment rich in this ion, such as the gastrointestinal tract, as bicarbonate is a virulence enhancer of this bacterium.Bioorganic & medicinal chemistry letters 03/2013; 23(6):1636-8. · 2.65 Impact Factor -
Article: Biomimetic CO(2) capture using a highly thermostable bacterial α-carbonic anhydrase immobilized on a polyurethane foam.
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ABSTRACT: The biomimetic approach represents an interesting strategy for carbon dioxide (CO(2)) capture, offering advantages over other methods, due to its specificity for CO(2) and its eco-compatibility, as it allows concentration of CO(2) from other gases, and its conversion to water soluble ions. This approach uses microorganisms capable of fixing CO(2) through metabolic pathways or via the use of an enzyme, such as carbonic anhydrase (CA, EC 4.2.1.1). Recently, our group cloned and purified a novel bacterial α-CA, named SspCA, from the thermophilic bacteria, Sulfurihydrogenibium yellowstonense YO3AOP1 living in hot springs at temperatures of up to 110°C. This enzyme showed an exceptional thermal stability, retaining its high catalytic activity for the CO(2) hydration reaction even after being heated at 70°C for several hours. In the present paper, the SspCA was immobilized within a polyurethane (PU) foam. The immobilized enzyme was found to be catalytically active and showed a long-term stability. A bioreactor containing the "PU-immobilized enzyme" (PU-SspCA) as shredded foam was used for experimental tests aimed to verify the CO(2) capture capability in conditions close to those of a power plant application. In this bioreactor, a gas phase, containing CO(2), was put into contact with a liquid phase under conditions, where CO(2) contained in the gas phase was absorbed and efficiently converted into bicarbonate by the extremo-α-CA.Journal of Enzyme Inhibition and Medicinal Chemistry 02/2013; · 1.62 Impact Factor -
Article: Biochemical properties of a new α-carbonic anhydrase from the human pathogenic bacterium, Vibrio cholerae.
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ABSTRACT: Abstract Vibrio cholerae, a Gram-negative bacterium, is the causative agent of cholera and colonizes the upper small intestine where sodium bicarbonate is present at a high concentration. Sodium bicarbonate is a potential inducer of virulence gene expression. Bacteria can increase cytosolic bicarbonate levels through the existence of transporter family proteins or through the action of metalloenzymes, called carbonic anhydrases (CAs, EC 4.2.1.1). Vibrio cholerae, lacking of transporter proteins in its genome, utilizes the CA system to accumulate bicarbonate into the cell suggesting a pivotal role of this metalloenzymes in the microbial virulence. Here, we report for the first time the characterization of the α-CA of V. cholerae (VchCA), which has been identified by translated genome inspection. The α-CA encoding gene was cloned and expressed in Escherichia coli and the recombinant protein purified to homogeneity. This investigation aimed to study the biochemical properties of VchCA and to provide preliminary insights in the field of this pathogen virulence. VchCA has a low esterase activity with 4-nitrophenyl acetate as substrate, and a high activity for the hydration of CO(2) to bicarbonate.Journal of Enzyme Inhibition and Medicinal Chemistry 01/2013; · 1.62 Impact Factor -
Article: The extremo-α-carbonic anhydrase (CA) from Sulfurihydrogenibium azorense, the fastest CA known, is highly activated by amino acids and amines.
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ABSTRACT: The α-carbonic anhydrase (CA, EC 4.2.1.1) from the extremophilic bacterium Sulfurihydrogenibium azorense (SazCA) was recently shown to be the fastest CA known. Here we investigated this enzyme for its activation with a series of amino acids and amines. The best SazCA activators were d-Phe, l-DOPA, l- and d-Trp, dopamine and serotonin, which showed activation constants in the range of 3-23nM. l- and d-His, l-Phe, l-Tyr, 2-pyridyl-methylamine and L-adrenaline were also effective activators (K(A)s in the range of 62-90nM), whereas d-Dopa, d-Tyr and several heterocyclic amines showed activity in the micromolar range. The good thermal stability, robustness, very high catalytic activity and propensity to be activated by simple amino acids and amines, make SazCA a very interesting candidate for biomimetic CO(2) capture processes.Bioorganic & medicinal chemistry letters 12/2012; · 2.65 Impact Factor -
Article: DNA cloning, characterization and inhibition studies of an alpha-carbonic anhydrase from the pathogenic bacterium Vibrio cholerae.
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ABSTRACT: We have cloned, purified and characterized an α-carbonic anhydrase (CA, EC 4.2.1.1) from the human pathogenic bacterium Vibrio cholerae, VchCA. The new enzyme has significant catalytic activity and an inhibition study with sulfonamides and sulfamates led to the detection of a large number of low nanomolar inhibitors, among which methazolamide, acetazolamide, ethoxzolamide, dorzolamide, brinzolamide, benzolamide and indisulam (KIs in the range of 0.69 - 8.1 nM). As bicarbonate is a virulence factor of this bacterium and since ethoxzolamide was shown to inhibit the in vivo virulence, we propose that VchCA may be a target for antibiotic development, exploiting a mechanism of action rarely considered up until now.Journal of Medicinal Chemistry 11/2012; · 4.80 Impact Factor
