STUDIES ON THE MODE OF ACTION OF DIPHTHERIA TOXIN

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Abstract
The effect of diphtheria toxin on subcellular components of protein synthesis was determined. Polyribosomes prepared from intoxicated guinea pigs functioned normally in an in vitro assay system, while the activity of soluble enzymes (transferases) from toxin-treated animals was significantly reduced. At high toxin dosages, this reduction was widespread, but when levels of toxin comparable to those which might be generated in a natural infection were given, inhibition of soluble enzyme activity was found only in extracts from heart and skeletal muscle. Possible nonspecific inhibition in the assay system due to interference by free toxin or by a serum component was eliminated.