Prejanò Mario, Marino Tiziana, Russo Nino
Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, 87036, Arcavacata di Rende (CS), Italy.
Chemistry. 2017 Jun 27;23(36):8652-8657. doi: 10.1002/chem.201700381. Epub 2017 Jun 7.
Lanthanides are an example of nonbiogenic metal species and have been widely used in crystallographic and spectroscopic studies to probe Mg /Ca binding sites in metalloproteins by replacing the native cofactor. Recently, a methanol dehydrogenase (MDH) enzyme containing cerium ion in the active site has been isolated from Methylacidiphilum fumariolicum bacterium. With the aim to highlight as metal ion substitution can be reflected in catalytic mechanism, a comparative DFT study between Ca- and Ce-MDH has been undertaken. The obtained potential energy surfaces (PES), for two considered reaction mechanisms (named A and B), indicate mechanism A (addition-elimination and protonation processes) as the favored for both the enzymes and show as the barrier for the rate-determining step of Ce-MDH requires 19.4 kcal mol .
镧系元素是非生物源金属物种的一个例子，已被广泛用于晶体学和光谱学研究，通过取代天然辅因子来探测金属蛋白中的镁/钙结合位点。最近，已从嗜热嗜酸甲基菌中分离出一种在活性位点含有铈离子的甲醇脱氢酶（MDH）。为了突出金属离子取代如何反映在催化机制中，对钙-MDH和铈-MDH进行了比较密度泛函理论（DFT）研究。对于两种考虑的反应机制（分别命名为A和B）所获得的势能面（PES）表明，机制A（加成-消除和质子化过程）对这两种酶来说都是更有利的，并且表明铈-MDH速率决定步骤的势垒需要19.4千卡·摩尔 。
