Characterization, Mechanism, and Application of Dipeptidyl Peptidase III: An Aflatoxin B-Degrading Enzyme from HNGD-TM15.

Aflatoxin B is a notorious mycotoxin with mutagenicity and carcinogenicity, posing a serious hazard to human and animal health. In this study, an AFB-degrading dipeptidyl-peptidase III mining from HNGD-TM15 (ADPP III) with a molecular weight of 79 kDa was identified. ADPP III exhibited optimal activity toward AFB at 40 °C and pH 7.0, maintaining over 80% relative activity at 80 °C. The key amino acid residues that affected enzyme activity were identified as H450, E451, H455, and E509 via bioinformatic analysis and site-directed mutagenesis. The degradation product of ADPP III toward AFB was verified to be AFD The zebrafish hepatotoxicity assay verified the toxicity of the AFB degradation product was significantly weaker than that of AFB. The result of this study proved that ADPP III presented a promising prospect for industrial application in food and feed detoxification.