A comparative depiction of the 3D structure of alcohol dehydrogenases. (A) Three-dimensional structure of MxaFI-MDH, PDB ID: 1W6S. Black bonds indicate ligand bonds, distances in Å, where the Asn261 ligand bond exceeds three Å and is not shown; (B) 3D structure of PedE-EDH, PDB ID: 1FLG. Black bonds indicate ligand bonds and distances are in Å. To highlight the specificity of asp, Asp316 ligand bonds are shown even though they are longer than three Å; (C) three-dimensional structure of XoxF2-MDH, PDB ID: 4MAE. Black bonds indicate coordination bonds and distances are in Å. The involvement of Asp301 in metal coordination can be notably found, resulting in an increased number of coordinations and, unlike Asp299, bidentate coordination; (D) 3D structure of PedH-EDH, PDB ID: 6ZCW black bonds indicate coordination bonds, distance unit is Å. It can be significantly found that Asp325 is involved in metal coordination, leading to an increased number of coordination, and is different from Asp323, and is bidentate. Combined with the difference in Fig. 3—Asp301 sequences, it can be seen that REEs-MDH/EDH have specific asp coordination bonds, forming a more robust binding pocket. The protein structure and active site were displayed using Pymol-software [74].