Specific Time Course of Peroxidase Oxidation in the Presence of SH-Containing Inhibitors : Comparison with the Inhibition of Polyphenoloxidase Activities

概要

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The time courses of the peroxidase reaction in presence of SH-containing inhibitors are very specific. After a lag period resulting from a transitory absence of reaction, the oxidation develops but its initial velocity is in some cases decreased. The duration of the lag period depends on the inhibitor concentration but can also be modified by incubating the inhibitor with hydrogen peroxide or with the enzyme. With respect to the inhibition of polyphenoloxidase activities, two kinds of action of SH-containing compounds might be recognized. The absence of the reaction observed during the first phase may be related to the chelation of Fe ions contained in the peroxidases, inducing then an inactivation of the enzymes. The beginning of the reaction, at the end of the lag period, might be due to the oxidation of the inhibitor SH-radicals by hydrogen peroxide or by some early oxidation products. The second action of the inhibitors might be due to a reduction of some early oxidation products such as quinones which prevents the formation of the coloured polymer. The initial velocity of the reaction is therefore lowered. This second phase depends on the nature of the substrate of the peroxidase reaction.
日本植物生理学会の論文