The molecule is a zwitterionic tautomer of diphthamide having an anionic carboxy group and a protonated primary amino group. It is a tautomer of a diphthamide.
(2S)-3-[2-[(3S)-4-amino-4-oxo-3-(trimethylazaniumyl)butyl]-1H-imidazol-5-yl]-2-azaniumylpropanoate