; and Agriculture Canada, Research Station, Harrow, Ontario, Canada NOR 1 GO (R.I.B.)Peroxidase activity in the seed coats of soybean (Clycine max [LI Merr.) is controlled by the Ep locus. We compared peroxidase activity in cell-free extracts from seed coat, root, and leaf tissues of three EpEp cultivars (Harosoy 63, Harovinton, and Coles) to three epep cultivars (Steele, Marathon, and Raiden). Extracts from the seed coats of EpEp cultivars were 100-fold higher in specific activity than those from epep cultivars, but there was no difference in specific activity in crude root or leaf extracts. lsoelectric focusing of root tissue extracts and staining for peroxidase activity showed that EpEp cultivars had a root peroxidase of identical isoelectric point to the seed coat peroxidase, whereas roots of the epep types were lacking that peroxidase, indicating that the Ep locus may also affect expression in the root. In seed coat extracts, peroxidase was the most abundant soluble protein in €p€p cultivars, whereas this enzyme was present only in trace amounts in epep genotypes, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Histochemical localization of peroxidase activity in seed coats of EpEp cultivars shows that the enzyme occurs predominately in the cytoplasm of hourglass cells of the subepidermis. No obvious difference in the gross or microscopic structure of the seed coat was observed to be associated with the Ep locus. These results suggest that soybean seed coat peroxidase may be involved in processes other than seed coat biosynthesis.

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Soybean (Glycine max) seed coats may contain large amounts of peroxidase enzyme. The release of peroxidase from whole seeds upon imbibition and the catalytic and antigenic properties of this enzyme were studied. Comparisons between high (Ep) and low (epep) peroxidase activity seeds demonstrated a lengthy (336 h) release of anionic peroxidase by Ep (Harovinton) cultivars following incubation in an aqueous environment. In its purified state, soybean seed coat peroxidase exhibited good catalytic activity towards phenolic substrates including eugenol, caffeic acid, and ferulic acid. Both leaf and stem cationic peroxidases behaved similarly to seed coat peroxidase in their substrate specificity. Furthermore, using guaiacol as a substrate at various pH levels and temperatures, soybean seed coat peroxidase had a greater enzyme stability and a wider range of action than other peroxidase enzymes. Polyclonal antibodies raised against cationic peanut peroxidase cross-reacted with soybean peroxidase in the presence and the absence of its glycosidic chains. This suggests homology in epitopes between the soybean and peanut polypeptide and (or) glycan chains. Key words: cross-reactivity, enzyme activity, peroxidase, polymerization, substrate.