– Gamma-Glutamylaminecyclotransferase is an enzyme that converts gamma-glutamylamines to free amines and 5-oxoproline which belongs to the gamma-glutamylcyclotransferase family. It shows high activity toward gamma-glutamyl-epsilon-lysine, derived from the breakdown of fibrin and contributes to degradation of proteins cross-linked by transglutaminases. It degrades the cross-link between a lysine and a glutamic acid residue from two proteins that have been cross-linked by transglutaminases. This protein adopts the newly identified cyclotransferase fold, observed in Gamma-Glutamylcyclotransferase, an enzyme with activity toward gamma-glutamyl-alpha-amino acids.