Cloning, characterization and anion inhibition study of the 未-class carbonic anhydrase (TweCA) from the marine diatom Thalassiosira weissflogii

详细信息    查看全文

• 作者：Sonia Del Prete ; Daniela Vullo ; Andrea Scozzafava ; Clemente Capasso ; Claudiu T. Supuran
• 关键词：Carbonic anhydrase ; 未-Class enzyme ; Anion ; Sulfonamide ; Diatom ; Carbon concentration mechanism
• 刊名：Bioorganic and Medicinal Chemistry
• 出版年：1 January, 2014
• 年：2014
• 卷：22
• 期：1
• 页码：531-537
• 全文大小：1068 K

文摘

We investigated the catalytic activity and inhibition of the 未-class carbonic anhydrase (CA, EC 4.2.1.1) from the marine diatom Thalassiosira weissflogii, TweCA. The enzyme, obtained by cloning the synthetic gene, was an efficient catalyst for the CO₂ hydration, its physiological reaction, with a k_cat of 1.3 脳 10⁵ s^鈭? and a k_cat/K_M of 3.3 脳 10⁷ M^鈭? s^鈭?. A range of inorganic anions and small molecules were investigated as inhibitors of TweCA. Chloride and sulfate did not inhibit the enzyme (K_Is >200 mM) whereas other halides and pseudohalides were submillimolar-millimolar inhibitors (K_Is in the range of 0.93-8.3 mM). The best TweCA inhibitors were hydrogen sulfide, sulfamate, sulfamide, phenylboronic acid and phenylarsonic acid, with K_Is in the range of 9-90 渭M, whereas acetazolamide inhibited the enzyme with a K_I of 83 nM. This is the first kinetic and inhibition study of a 未-class CA. However, these enzymes are widespread in the marine phytoplankton, being present in haptophytes, dinoflagellates, diatoms, and chlorophytic prasinophytes, contributing to the CO₂ fixation by sea organisms. A phylogenetic analysis with all five genetic families of CAs showed that 伪- and 未-CAs are evolutionarily more related to each other with respect to the 纬-CAs, although these three families clustered all together. On the contrary, the 尾- and 味-CAs are also related to each other but phylogenetically much more distant from the 伪-, 纬 and 未-CA cluster. Thus, the study of 未-CAs is essential for better understanding this superfamily of metalloenzymes and their potential biotechnological applications in biomimetic CO₂ capture processes, as these enzymes are part of the carbon concentrating mechanism used by many photosynthetic organisms.