Faster and sensitive zymographic detection of oxidases generating hydrogen peroxide. The case of diamine oxidase

The existing zymography method for the detection of diamine oxidase (DAO) activity has been improved by a new staining procedure with the aim to ameliorate its sensitivity. Both procedures used SDS-PAGE gels containing uniformly distributed entrapped peroxidase (that wouldn't migrate during electrophoresis). The new approach with 3,5-dichloro-2-hydroxybenzenesulfonate (DCHBS) as peroxidase substrate and with 4-amino-antipyrine as color stabilizer allows a more sensitive detection of DAO when compared to the previously reported o-phenylenediamine (o-PDA) as peroxidase substrate. The newly improved method appears faster, simple and environmentally friendly. It can be used for most of oxidases releasing hydrogen peroxide as reaction product. [Display omitted] •Diamine oxidase (DAO) catalyses the oxidative deamination of biogenic amines with the release of H2O2.•Zymography with entrapped peroxidase in PAA gel allows DAO detection in presence of interfering enzymes.•The Zymography method with DCHBS-AAP is more sensitive compared than that with o-PDA for DAO detection.•The method allows determination of various oxidases, even in the presence of interfering catalase.•The chromogen DCHBS-AAP is safer and less toxic than o-PDA.