(A) Catalysis of acetaldehyde to acetic acid by ALDH/RALDH family proteins. (B) Phylogenetic tree of 19 human ALDH genes encoding for corresponding members of ALDH superfamily. The percentages of replicate trees in which the associated taxa clustered together in the bootstrap test (500 replicates) are shown next to the branches. Branch lengths are in the same units as those of the evolutionary distances. (C) The substrate tunnel entrances of RALDHs and ALDH2 shown as surface models and are surrounded by a black dotted line. Surface representation of RALDH1-3 and ALDH2 were created based on Protein Data Bank (PDB) code 4WB9, 6ALJ, 5FHZ (chain D) and 1O01, respectively, and depicted using the molecular graphics system PyMOL (Ver. 2.4, Schrodinger, LLC).