Reassessing of enzymes degrading mycotoxins at acidic pH

Abstract

Mycotoxins contaminate different commodities, thus endangering well being of humans and animals. In the present study, three enzymes – peroxidase, laccase, and glucose oxidase – were reanalyzed using computer modeling for their catalytic activity at acidic pH in a sample group of 18 mycotoxins. Fungal glucose oxidase was found to be catalytically active with the largest number of mycotoxins tested in silico according to results of molecular docking, and was further selected for in vitro experiments. Initially glucose oxidase activity was measured with AChE assay and later it was coupled to horseradish peroxidase for direct detection of mycotoxin transformations (three substrates and three non-substrates). On the basis of these results, it became possible to generalize and formulate model predicting Michaelis constants of glucose oxidase towards some other possible substrates, including mycotoxins not tested currently in vitro. The glucose oxidase showing maximal activity at approximately pH 5.5 can be potentially applied not only to detect mycotoxins at acidic pHs (e.g., when combining with peroxidase and chromophore/fluorophore co-substrate) but also to treat them enzymatically (e.g., during silaging).