Diphtheria Toxin-dependent Adenosine Diphosphate Ribosylation of Aminoacyl Transferase II and Inhibition of Protein Synthesis

In the presence of diphtheria toxin, the adenosine diphosphate ribose portion of nicotinamide adenine dinucleotide was transferred to aminoacyl transferase II obtained from rat liver. The reaction resulted in a concurrent inactivation of this particular enzyme, one of the supernatant factors which assemble amino acids into polypeptide chain. The linkage of ADP-ribose to aminoacyl transferase II appeared to be of covalent nature. The reaction was reversible. Diptheria toxin may act as an enzyme or a catalytic cofactor in this reaction.