This region contains the Glutathionylspermidine synthase enzymatic activity EC:6.3.1.8. This is the C-terminal region in bi-enzymes. Glutathionylspermidine (GSP) synthetases of Trypanosomatidae and Escherichia coli couple hydrolysis of ATP (to ADP and Pi) with formation of an amide bond between spermidine and the glycine carboxylate of glutathione (gamma-Glu-Cys-Gly). In the pathogenic trypanosomatids, this reaction is the penultimate step in the biosynthesis of the antioxidant metabolite, trypanothione (N1,N8-bis-(glutathionyl)spermidine), and is a target for drug design. This region, the pre-ATP grasp region, probably carries the substrate-binding site.
Jiyao W et al.(2023). "The conserved domain database in 2023.",