diphtheria toxin A

Diphtheria toxin A is the **enzymatically active portion (fragment A) of diphtheria toxin**, a protein exotoxin produced by toxic strains of *Corynebacterium diphtheriae* following infection by a bacteriophage. The diphtheria toxin is a two-part (A+B) protein: **fragment A is responsible for the ADP-ribosylation and inactivation of elongation factor 2 (EF-2)**, which halts protein synthesis and results in cell death[9][12][11]. Diphtheria toxin A has been widely adapted as the **cytotoxic payload in recombinant fusion protein therapies (immunotoxins or fusion toxins)** for the targeted killing of malignant or pathological cells in cancer, autoimmune, and other diseases. It is not used clinically as a standalone drug but as a component in engineered therapeutics where the targeting domain directs the cytotoxic A fragment to specific cell populations[2].

Other names

diphtheria toxin fragment ADTA