Fig. 4: The structure and mechanism implications of ALDH.

a The structure of ALDH (PBD ID:8IXI) is shown with subunit 1 in light orange and subunit 2 in purple. b ALDH comprises three domains: the substrate-binding domain (residues 1-99, fuchsia), the NAD⁺-binding domain (residues 100-280, green), and the helical domain (residues 280-294, cyan). c Detection of 5-oxopentanoic acid in HPLC. The red and purple profiles represented the standard sample of glutarate and glutaraldehyde, while the green profile represented the sample of whole-cell catalysis, with the peak of 5-oxopentanoic acid indicated by an arrow. d Concentration changes of the substrate (glutaraldehyde: blue), intermediate (5-oxopentanoic acid: red), and product (glutarate: green) during in vitro catalysis of pure enzymes. e Initial reaction rate using different pH conditions. f Tyr88 residue was mutated to alanine to verify its role in the catalytic reaction. g Reaction mechanism for the oxidation of glutaraldehyde by ALDH. GLD Glutaraldehyde, GLT Glutarate. h DFT-computed Gibbs free energies (in kcal/mol) at the CPCM (water) level of theory and transition-state structures (carbon: gray, hydrogen: white, oxygen: red, nitrogen: blue, angles are shown in o, and distances are shown in Å). n = 3 independent experiments. Data are presented as mean values ± SD. Source data are provided as a Source Data file.