Sodium diethyldithiocarabamate (la) has been widely used as a copper trapping reagent. Thus, the inhibition of an enzymatic reaction by la has been regarded as a proof of the participation of copper in the reaction.'However, we previously noted that the inhibitory effect of la on the oxygenase activity of L-tryptophan 2, 3-di-oxygenase was caused by its rapid reaction with hydrogen peroxide, the activator of the enzyme, instead of the chelation with ...
