Diphthamide_syn, diphthamide synthase, catalyses the last amidation step of diphthamide biosynthesis using ammonium and ATP. Diphthamide synthase is evolutionarily conserved in eukaryotes. Diphthamide is a post-translationally modified histidine residue found on archaeal and eukaryotic translation elongation factor 2 (eEF-2) [1]. In some members of this family e.g. Swiss:Q12429, this domain is associated with Pfam:PF01042. The enzyme classification is EC:6.3.1.14.

1: Chemogenomic approach identified yeast YLR143W as diphthamide synthetase. Su X, Lin Z, Chen W, Jiang H, Zhang S, Lin H; Proc Natl Acad Sci U S A. 2012;109:19983-19987. PMID:23169644