Organism and molecular-level responses of superoxide dismutase interaction with 2-pentanone

2-Pentanone is an excellent organic solvent and extractant, which is widely used in industrial production. 2-Pentanone is harmful to soil organisms when it enters the soil. However, current studies have not clarified the response of the antioxidant enzyme superoxide dismutase (SOD) to 2-Pentanone and its mechanism. In this study, the response of earthworm antioxidant enzyme SOD to 2-Pentanone and its molecular mechanism was investigated at organism molecular levels. The results showed that the SOD activity of earthworms under 2-Pentanone stress was significantly inhibited, and the inability of superoxide anion radicals (·O₂^-) to be scavenged in time might be one of the reasons for the increase of lipid peroxidation. Under 2-Pentanone exposure conditions, catalase (CAT), an antioxidant enzyme closely related to SOD, and the total antioxidant capacity (T-AOC) of earthworms were activated to resist oxidative damage. On the other hand, the observation of earthworm microstructure provided evidence of a direct risk of 2-Pentanone on earthworm body wall tissues. Molecular-level assays have shown that 2-pentanone altered the secondary structure of SOD, which further led to the loosening of the SOD backbone structure and the extension of the polypeptide chain. On the other hand, 2-pentanone quenched the endogenous fluorescence of SOD in the form of static quenching and formed the 2-pentanone/SOD complex. Molecular simulation results suggested that 2-pentanone tended to bind on the surface of SOD rather than close to the active site, and it is speculated that the alteration of SOD structure is the key reason for the change in its activity. This study enriches the toxicological data of 2-Pentanone on soil organisms, thus responding to the current concerns about its ecological risk.