Institute of Biosciences and Bioresources, CNR, Via Pietro Castellino 111, 80131 Napoli, Italy.
Proteomics &.
Molecules. 2020 May 31;25(11):2564. doi: 10.3390/molecules25112564.
The interconversion of CO and HCO is catalyzed by a superfamily of metalloenzymes, known as carbonic anhydrases (CAs, EC 4.2.1.1), which maintain the equilibrium between dissolved inorganic CO and HCO. In the genome of , a Gram-negative bacterium typically colonizing the lower intestine of warm-blooded organisms, the cyn operon gene includes the CynT gene, encoding for a β-CA, and CynS gene, encoding for the cyanase. CynT (β-CA) prevents the depletion of the cellular bicarbonate, which is further used in the reaction catalyzed by cyanase. A second β-CA (CynT2 or Can or yadF), as well as a γ and ι-CAs were also identified in the genome. CynT2 is essential for bacterial growth at atmospheric CO concentration. Here, we characterized the kinetic properties and the anion inhibition profiles of recombinant CynT2. The enzyme showed a good activity for the physiological CO hydratase reaction with the following parameters: k = 5.3 × 10 s and k/K = of 4.1 × 10 M s. Sulfamide, sulfamate, phenylboronic acid, phenylarsonic acid, and diethyldithiocarbamate were the most effective CynT2 inhibitors (K = 2.5 to 84 µM). The anions allowed for a detailed understanding of the interaction of inhibitors with the amino acid residues surrounding the catalytic pocket of the enzyme and may be used as leads for the design of more efficient and specific inhibitors.
CO 和 HCO 的相互转化由碳酸酐酶（CA，EC 4.2.1.1）超家族金属酶催化，该酶维持溶解无机 CO 和 HCO 之间的平衡。在革兰氏阴性菌的基因组中，通常定植于温血动物的下肠道， Cyn 操纵子基因包括 CynT 基因，编码β-CA，以及 CynS 基因，编码氰酶。CynT（β-CA）防止细胞碳酸氢盐的耗尽，进一步用于氰酶催化的反应中。在基因组中还鉴定了第二种β-CA（CynT2 或 Can 或 yadF）以及γ和ι-CA。CynT2 对于细菌在大气 CO 浓度下的生长是必需的。在这里，我们表征了重组 CynT2 的动力学特性和阴离子抑制特性。该酶对生理 CO 水合酶反应表现出良好的活性，其参数为：k = 5.3×10 s 和 k/K = 4.1×10 M s。磺胺、磺胺酸盐、苯硼酸、苯胂酸和二乙二硫代氨基甲酸盐是 CynT2 最有效的抑制剂（K = 2.5 至 84µM）。阴离子允许详细了解抑制剂与酶催化口袋周围氨基酸残基的相互作用，并可作为设计更有效和更特异抑制剂的先导。
