Biochemical oxygen activation as the basis for the physiological action of tetrachlorodecaoxide (TCDO).

Oxidation of methionine, 4-(methylthio)-2-oxobutyric acid (KMB), or 1-aminocyclopropane carbonic acid (ACC) are indicator reactions for activated oxygen species such as singlet oxygen (1O2), OH.-radical like oxidants, superoxide anion (O2.-), hydrogen peroxide (H2O2) or activated hemo-iron complexes like peroxidase- or catalase-"compound I". Methionine is oxidized by OH. as well as by 1O2 forming ethylene, but not by tetrachloro-decaoxygen complex (TCDO) in the absence or presence of catalytic hemoproteins such as peroxidase, hemoglobin or myoglobin. Both KMB and ACC are oxidized by TCDO under the catalysis of the above hemo-proteins where neither catalase nor superoxide dismutase are inhibitors. TCDO hemo-protein complex is an oxidant with similar properties as peroxidase-compound I and can clearly be differentiated from O2.-, H2O2, OH. and 1O2.