Diphtheria Toxin Structure Pictured here is the x-ray crystal structure of diphtheria toxin. It is a single polypeptide chain weighing 58-kDa. The following buttons will change how the protein is viewed. Push the button to change the molecules into wireframe models. Push the button to change the molecules into cartoon models.
Diphtheria toxin has an alpha, beta structural motif connected by loops.
These fragments are held together by disulfide bonds. Here you can see how diphtheria toxin is conformationally restricted by two disulfide bonds. These two chains each provide a unique function to the toxin. Hydrophobic sequences within these helices are essential for insertion into the membrane and translocation. For further illustration, depicted below, courtesy of Dr. Kenneth Todar from the University of Wisconsin , is the diphtheria toxin monomer .