Carbonic Anhydrase Inhibitors. DNA Cloning, Characterization, and Inhibition Studies of the Human Secretory Isoform VI, a New Target for Sulfonamide and Sulfamate Inhibitors

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• 作者：Isao Nishimori ; Tomoko Minakuchi ; Saburo Onishi ; Daniela Vullo ; Andrea Scozzafava ; Claudiu T. Supuran
• 刊名：Journal of Medicinal Chemistry
• 出版年：2007
• 出版时间：January 25, 2007
• 年：2007
• 卷：50
• 期：2
• 页码：381 - 388
• 全文大小：250K
• 年卷期：v.50,no.2(January 25, 2007)
• ISSN：1520-4804

文摘

The secretory isozyme of human carbonic anhydrase (hCA, EC 4.2.1.1), hCA VI, has been cloned, expressed,and purified in a bacterial expression system. The kinetic parameters for the CO₂ hydration reaction provedhCA VI to possess a k_cat of 3.4 × 10⁵ s^-1 and k_cat/K_M of 4.9 × 10⁷ M^-1 s^-1 (at pH 7.5 and 20 C). hCA VIhas a significant catalytic activity for the physiological reaction on the same order of magnitude as theubiquitous isoform CA I or the transmembrane, tumor-associated isozyme CA IX. A series of sulfonamidesand one sulfamate have been tested for their interaction with this isozyme. Simple benzenesulfonamideswere rather ineffective hCA VI inhibitors, with inhibition constants in the range of 1090-6680 nM. Betterinhibitors were detected among such derivatives bearing 2- or 4-amino-, 4-aminomethyl-, or 4-hydroxymethylmoieties or among halogenated sulfanilamides (K_I values of 608-955 nM). Some clinically used compounds,such as acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide, dorzolamide, brinzolamide,topiramate, sulpiride, and indisulam, or the orphan drug benzolamide, showed effective hCA VI inhibitoryactivity, with inhibition constants of 0.8-79 nM. The best inhibitors were brinzolamide and sulpiride (K_Ivalues of 0.8-0.9 nM), the latter compound being also a CA VI-selective inhibitor. The metallic tastereported as a side effect after the treatment with systemic sulfonamides may be due to the inhibition of thesalivary CA VI. Some of the compounds investigated in this study might be used as additives in toothpastesfor reducing the acidification produced by the relevant CO₂ hydrase activity of enamel CA VI, which leadsto the formation of protons and bicarbonate and may have a role in cariogenesis.