How Can Methanol Dehydrogenase from Methylacidiphilum fumariolicum Work with the Alien CeIII Ion in the Active Center? A Theoretical Study.

Lanthanides are an example of nonbiogenic metal species and have been widely used in crystallographic and spectroscopic studies to probe Mg2+ /Ca2+ 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-1 .