Electrophoretic and Immunoelectrophoretic Patterns of Extracellular Diphtheria Proteins from Culture Filtrates of Different Iron Concentrations

Abstract

IN cultures of Corynebacterium diphtheriae the toxin is produced only within a relatively narrow range of iron concentration. Excess of iron inhibits toxin formation, but the mechanism of this phenomenon is not explained. Toxigenicity is strictly associated with the presence of prophage in diphtheria bacillus cells, and it has been recently suggested that iron probably affects toxin production by causing induction of the prophage–host system¹. At iron excess a certain amount of atoxic, extracellular protein is found in the culture filtrate, but their physico-chemical and immunological properties are little known. A closer characterization of these components, which will be hereafter referred to as ‘Fe-proteins’, appears useful for work on toxin formation.