In enzymology, a glutamate—ethylamine ligase () is an enzyme that catalyzes the chemical reaction
ATP + L-glutamate + ethylamine ADP + phosphate + N5-ethyl-L-glutamine
The 3 substrates of this enzyme are ATP, L-glutamate, and ethylamine, whereas its 3 products are ADP, phosphate, and N5-ethyl-L-glutamine.
This enzyme belongs to the family of ligases, specifically those forming carbon-nitrogen bonds as acid-D-ammonia (or amine) ligases (amide synthases). The systematic name of this enzyme class is L-glutamate:ethylamine ligase (ADP-forming). Other names in common use include N5-ethyl-L-glutamine synthetase, theanine synthetase, and N5-ethylglutamine synthetase.
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