Diphtheria toxin acts by

The diphtheria toxin acts by inhibiting protein synthesis. Specifically, a fragment B heparin binding and fragment A inhibits polypeptide chain elongation in the presence of nicotinamide adenine dinucleotide by inactivating the elongation factor EF-2. It has a special affinity for ceain tissues such as the myocardium, adrenals and nerve endings. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 240