Inertness of horseradish peroxidase to 2,4-dichlorophenoxyacetic acid [IAA, indoleacetic acid, Armoracia lapathifolia]
1980
Paul, K.G. | Oehrman, B. (Umeaa Univ. (Sweden). Dept. of Chemistry)
The possibility of mutual effects of 2,4-D and horseradish (Armoracia lapathifolia L.) peroxidase on each other has been explored by four procedures. (i) Compounds I, II, and III of horseradish peroxidase (HRP) and H(,2)O(,2) were exposed to 2,4-D. (ii) Extracts from batchwise operations of HRP + H(,2)O(,2) and 2,4-D were analyzed for oxidation products by means of thin layer chromatography. (iii) The velocity of the IAA oxidase reaction with HRP as catalyst, and (iv) K(, m) and V(,8) of the overall peroxidation of guaiacol by HRP + H(,2)O(,2) were determined in the absence and presence of 2,4-D. The results failed to show any effect of 2,4-D; only at very high concentrations did 2,4-D slightly inhibit the oxidation of IAA by one isoperoxidase. It is concluded that 2,4-D does not promote growth in plants by hampering a peroxidase-catalyzed IAA oxidation. It seems probable that 2,4-D perturbs the isoperoxidase pattern by acting at some step prior to the release of the enzyme from its site of synthesis
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