2.6.1.104 enzyme shares the common type 1 aspartate aminotransferase fold with residues from both monomers forming the active site. The structure of the enzyme alone reveals the internal aldimine form of NtdA with the cofactor pyridoxal phosphate covalently attached to Lys247. The addition of glutamate results in formation of pyridoxamine phosphate. Co-crystallization with kanosamine 6-phosphate results in the formation of the external aldimine. Only alpha-D-kanosamine 6-phosphate is observed in the active site of NtdA, not the beta-anomer 727966