Indoleacetate oxidase activity of horseradish and other plant peroxidase isozymes<xref ref-type="fn" rid="fn1"><sup>1</sup></xref>

Abstract

Zymographic analyses were carried out on a commercial peroxidase preparation of horseradish (Cochlearia armorada) and crude extracts from several plant materials, such as roots of turnip, radish, spinach, sweet potato and morning glory, regarding the dual catalytic activities of peroxidase- IA oxidase isozymes. A standard reacting mixture for the oxidase stain contained IA, TCP and Fast Blue BB salt as substrate, promoting agent and dye coupler, respectively. An unidentified intermediate (or intermediates) resulting from enzymatic IA degradation was demonstrated to be coupled with the diazonium salt and to form an insoluble complex. At least four cathodal and four anodal peroxidase bands were located in the horseradish preparation, the former appearing as dark IA oxidase bands and the latter as very faint bands. In the extracts from plant materials, less than half of the total peroxidase bands appeared as heavy to faint IA oxidase bands, whereas the remaining ones did not appear in the same condition as that for the horseradish IA oxidase stain. Furthermore, it was noted that the intensity of each of the peroxidase bands was not always correlated with that of the corresponding oxidase bands.