Diphthamide

• 2-amino- 3-[ 2 - (3 -carbamoyl -3- trimethylammonio -propyl) -3H -imidazol- 4-yl] propanoate
• (2S ) -3 - {2 - [ (3R)- 4-amino -4-oxo -3-( trimethylazaniumyl ) butyl] -1H- imidazol-4 -yl} -2- azaniumylpropanoat (IUPAC)

Template: Infobox chemical / molecular formula search available

Diphthamide is a derivative of histidine amino acid in the protein plays a role only at a step of elongation. Other biological functions and an occurrence outside of the protein are not known. The name is derived from the diphtheria toxin, its inhibitory effect on diphthamide attaches. The comparable toxins exotoxin A and cholera toxin also act on diphthamide.

When elongation in eukaryotes and archaea thereby the necessary elongation contains 2 (EF - 2) in its peptide chain to a position in place of the amino acid histidine derived diphthamide. Biosynthesis is complex, there are at least seven proteins involved. In the course of the biosynthesis of histidine is modified in the built- in the peptide chain to form diphthamide.

3- amino-3- carboxypropyl group from S-adenosylmethionine is transmitted as a radical of the histidine. Subsequently, a methyltransferase catalyzes the trimethylation and a synthase amidation.