The catalytic mechanism of the mitochondrial methylenetetrahydrofolate dehydrogenase/cyclohydrolase (MTHFD2)
Fig 5
The left column shows the resonance states (Φ1D, Φ2D, and Φ3D) used to describe the dehydrogenase activity. The middle column shows snapshots of the reactant, intermediate and product state, which are depicted as stick and colored by elements (C atoms: white for THF and orange for NAD+/NADH). The hydroxide is shown as a sphere and colored in salmon red. In the optimized reactant geometry, the distance between the reactive C atom of CH2-THF and the reactive C atom of NAD+ is 3.1 Å, with the transferring hydrogen at 2.1 Å from the acceptor C atom. The last column shows snapshots representing the water reorganization from the reactant state to product state. The water molecules within 7Å from the reactive C atom of THF are shown as both stick and sphere and colored red for oxygen atoms, while for the water molecules beyond 7Å are only shown as blue spheres to distinguish them.