Gamma-Glutamylamine Cyclotransferase (gGACT)

Proteolytic degradation of crosslinked fibrin results in the formation of the isodipeptide L-gamma-glutamyl-L-epsilon-lysine. Breakdown of this molecule is catalyzed by the gamma-glutamylamine cyclotransferase A2LD1, which cyclizes the gamma-glutamyl moiety to produce 5-oxo-L-proline and free alkylamine.The deduced 153-amino acid protein has a calculated molecular mass of 17.3 kD.

Crystallization of GGACT in the presence of the product 5-oxo-L-proline unambiguously identified the active-site cavity on the side of the barrel adjacent to strands beta-1 and beta-5. Mutation of glu82 rendered GGACT inactive, but it did not alter the GGACT structure.