The carbonic anhydrases (CAs, EC 4.2.1.1) catalyse a simple but physiologically crucial reversible reaction, the carbon dioxide hydration with the production of bicarbonate and protons. In the last years, and especially, to the rapid emergence of the bacterial antibiotic resistance that is occurring worldwide, the understanding of the function of bacterial CAs has increased significantly. Recently, a new CA-class (ι-CA) was discovered in the marine diatom T. pseudonana. It has been reported that bacterial genomes may contain genes with relevant homology to the diatom ι-class CA. Still, the catalytic activity of the enzyme encoded by the gene was not investigated. Thus, herein, for the first time, we cloned, expressed, and purified the recombinant bacterial ι-CA (acronym BteCAι) identified in the genome of Burkholderia territorii. The recombinant BteCAι resulted in a good catalyst for the hydration of CO2 to bicarbonate and protons, with a kcat of 3.0 × 105 s -1 and kcat/KM of 3.9 × 107 M -1 s -1, and is also sensitive to inhibition by the sulphonamide acetazolamide. Furthermore, with the aid of the protonography, it has been demonstrated that BteCAι can be present as a dimer. This result is corroborated by the construction of a molecular model of BteCAι, which showed that the enzyme is formed by two equivalent monomers having a structure similar to a butterfly.

中文翻译：

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细菌ι-碳酸酐酶：在革兰氏阴性细菌土伯克霍尔德氏菌的基因组中鉴定出的一类新的活性碳酸酐酶。

碳酸酐酶（CA、EC 4.2.1.1）催化一种简单但生理学上至关重要的可逆反应，即二氧化碳水合并产生碳酸氢根和质子。在过去几年中，特别是随着世界范围内细菌抗生素耐药性的迅速出现，人们对细菌 CA 功能的了解显着增加。最近，在海洋硅藻 T.pseudonana 中发现了一个新的 CA 类（ι-CA）。据报道，细菌基因组可能含有与硅藻ι类CA具有相关同源性的基因。尽管如此，该基因编码的酶的催化活性尚未得到研究。因此，在此，我们首次克隆、表达和纯化了在土伯克霍尔德氏菌基因组中鉴定的重组细菌ι-CA（缩写BteCAι）。重组BteCAι为CO2水合生成碳酸氢盐和质子提供了良好的催化剂，kcat为3.0 × 105 s -1 ，kcat/KM为3.9 × 107 M -1 s -1 ，并且对抑制也敏感磺胺乙酰唑胺。此外，借助质子照相术，已经证明BteCAι可以作为二聚体存在。BteCAι分子模型的构建证实了这一结果，该模型表明该酶是由两个具有类似于蝴蝶结构的等效单体形成的。