Studies on Auxin Protectors. V. On the Mechanism of IAA Protection by Protector-I of the Japanese Morning Glory

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Abstract
The mechanism of auxin protection by auxin protector-I (Pr-I) of the Japanese morning glory was studied in vitro. Four lines of evidence indicate that Pr-I acts as a strong reductant which prevents the peroxidase-catalyzed oxidation of IAA: 1) The kinetics of the reaction are best explained on this basis. 2) The Pr-I-induced lag preceding auxin destruction by peroxidase is completely eliminated by a strong oxidant such as H2O2 at a concentration which does not appreciably affect the reaction rate. 3) Strong organic reductants mimic the Pr-I-induced lag. And 4) when the reaction rate is altered by varying the concentrations of the reactants, or the temperature, the length of the Pr-I-induced lag varies inversely with the reaction rate.
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