Soluble peroxidase from winter wheat seedlings with phenoloxidase-like activity.

Peroxidase isozymes from winter wheat (Triticum aestivum L. cv Orso) seedlings extracts showed phenoloxidase-like activity, becoming visible on polyacrylamide gels also in the absence of hydrogen peroxide. The results obtained after a characterization of the two activities, based on their substrate specificity, on their selective inhibition, and on the possible occurrence of artifacts, suggested the existence of polyfunctional peroxidase isozymes. Different isozymes possessing only phenol oxidase activity were not found in the same plant material. This appears to be the first evidence of phenoloxidase-acting isoperoxidases in winter wheat.