Faculty of Medicine and Health Technology, University of Tampere, 33100 Tampere, Finland.
Neurofarba Dept., Sezione di Scienze Farmaceutiche e Nutraceutiche, Università degli Studi di Firenze, Via U. Schiff 6, Sesto Fiorentino, 50019 Florence, Italy.
Molecules. 2018 Nov 28;23(12):3112. doi: 10.3390/molecules23123112.
We report the cloning and catalytic activity of a β-carbonic anhydrase (CA, EC 4.2.1.1), isolated from the pathogenic protozoan , EhiCA. This enzyme has a high catalytic activity for the physiologic CO₂ hydration reaction, with a k of 6.7 × 10⁵ s and a k/K of 8.9 × 10⁷ M × s. An anion inhibition study of EhiCA with inorganic/organic anions and small molecules revealed that fluoride, chloride, cyanide, azide, pyrodiphosphate, perchlorate, tetrafluoroborate and sulfamic acid did not inhibit the enzyme activity, whereas pseudohalides (cyanate and thiocyanate), bicarbonate, nitrate, nitrite, diethyldithiocarbamate, and many complex inorganic anions showed inhibition in the millimolar range (Ks of 0.51⁻8.4 mM). The best EhiCA inhibitors were fluorosulfonate, sulfamide, phenylboronic acid and phenylarsonic acid (Ks in the range of 28⁻86 μM). Since β-CAs are not present in vertebrates, the present study may be useful for detecting lead compounds for the design of effective enzyme inhibitors, with potential to develop anti-infectives with alternative mechanisms of action.
我们报道了一种β-碳酸酐酶（CA，EC 4.2.1.1）的克隆和催化活性，该酶来自致病原生动物 。这种酶对生理 CO₂水合反应具有很高的催化活性，k 值为 6.7×10⁵ s，k/K 值为 8.9×10⁷ M×s。对 EhiCA 的阴离子抑制研究表明，无机/有机阴离子和小分子中，氟化物、氯化物、氰化物、叠氮化物、焦磷酸、高氯酸盐、四氟硼酸盐和氨基磺酸不会抑制酶活性，而拟卤化物（氰酸盐和硫氰酸盐）、碳酸氢盐、硝酸盐、亚硝酸盐、二乙基二硫代氨基甲酸盐和许多复杂的无机阴离子在毫摩尔范围内显示抑制作用（Ks 值为 0.51⁻8.4 mM）。最好的 EhiCA 抑制剂是氟磺酸盐、磺胺、苯硼酸和苯胂酸（Ks 值在 28⁻86 μM 范围内）。由于β-CAs 在脊椎动物中不存在，因此本研究可能有助于检测用于设计有效酶抑制剂的先导化合物，具有开发具有替代作用机制的抗感染药物的潜力。
