The Reactivity of 4-Thiouridine with Peroxidase and Superoxide Radicals

Rice leaf slices stimulated with blast fungus hyphal component reduced nitroblue tetrazolium in a damped oscillatory profile with relaxing half wavelength in a medium containing glucose, when the respective rate of reduction was plotted against the function of time after the application of blast fungus hyphal component. In the presence of 110μm FAD and glucose, the wave number of the reduction profile increased 4- to 5-fold when compared to that in the absence of exogenous FAD. Exogenous FAD in the increasing concentration of 70 to 110 μm, which was added in the presence of glucose, gave a positive heterotropic-like response upon the reduction of nitroblue tetrazolium with rice leaf slices which were press-injured and stimulated. Exogenous pyrroloquinoline quinone in the increasing concentration of 10^?3 to 10^?1 μm, which was added in the presence of glucose, gave an inhibition upon the reduction. From sediment of the homogenate of stimulated rice leaf slices, the nitroblue tetrazolium reducing redox-enzyme system was solubilized by Triton X-100 and was electrophoretically isolated in a sharp blue band on a polyacrylamide slab gel containing Triton X-100, when the electrophoresed gel was stained by nitroblue tetrazolium or Coomassie brilliant blue. In the solubilized solution, the presence of b-type cytochrome was observed by the oxidation-reduction difference spectrum.