EFFECT OF XANTHENE DYES ON PEROXIDASE-CATALYZED OXIDATION OF INDOLE-3-ACETIC-ACID

The effect of xanthene dyes on the oxidation of indole-3-acetic acid ( IAA) catalyzed by horseradish peroxidase was studied by the chemilumin escent and spectrophotometric methods. It was found that the addition of dyes to the IAA-HRP-oxygen system resulted in: appearance of emissi on in the region of dye fluorescence, increase in the quantum chemilum inescence intensity, decrease in the emission duration, acceleration o f IAA oxidation, and slow bleaching of the dyes. Moreover, the effect of the HRP-hydrogen peroxide system on the xanthene dyes was investiga ted. It was found that the dyes were bleached in the presence of HRP a nd hydrogen peroxide. The bleaching was accompanied by chemiluminescen ce. The spectrum of chemiluminescence was identical to that of dye flu orescence. The experimental results lead to the conclusion that all sp ectral and kinetic variations of the chemiluminescence from the IAA-HR P-oxygen system which are caused by the addition of xanthene dyes is t he result of IAA-dye co-oxidation. Earlier published reports regarding energy transfer from electronically excited species generated in the IAA-HRP-oxygen system to the xanthene dyes seem to be unfounded.