Abstract
Summary
A nontoxigenic strain of C. diphtheriae, when grown in medium of low iron concentration, produced a nontoxic extracellular protein in amounts similar to the toxin produced by toxigenic β-prophage-infected cells of the same parent strain. Excretion of both the nontoxic protein and toxin was found to be completely suppressed by increasing the environmental iron concentration. A variety of analytical procedures indicated that the nontoxic protein has many chemical and physical similarities to diphtheria toxin, but differs in immunochemical and biological properties. These findings strongly support the concept that diphtheria toxin is a protein component of cytochrome and thus help to provide insight into the probable mechanisms of production and excretion of this bacterial exotoxin.
Get full access to this article
View all access options for this article.