Diphthine—ammonia ligase

In enzymology, a diphthine-ammonia ligase (EC 6.3.1.14, diphthamide synthase, diphthamide synthetase) is an enzyme that catalyzes the chemical reaction

The 3 substrates of this enzyme are ATP, diphthine, and NH₃, whereas its 3 products are ADP, phosphate, and diphthamide.

This enzyme belongs to the family of ligases, specifically those forming carbon-nitrogen bonds as acid-D-amino-acid ligases (peptide synthases). The systematic name of this enzyme class is diphthine:ammonia ligase (ADP-forming). Other names in common use include diphthamide synthase, and diphthamide synthetase.