New derivatives of argininosuccinic acid in the urine of a patient with argininosuccinicaciduria.

The urine of a patient with argininosuccinicaciduria contains several previously undescribed compounds that can be derived chemically from argininosuccinic anhydride (I). One of the major compounds is 8-carboxy-2-carboxymethyl-3-oxo-2,3,5,6,7,8-hexa-hydro-1H-imidazo [1,2-a][1,3]diazepine, which exists as two diastereoisomers that are readily interconvertible at pH5. The corresponding ring-opened monocyclic diazepines are also present, as well as traces of the isomeric hexahydroimidazodiazepines that are formally related to argininosuccinic anhydride (II). The formation and stereochemistry of these compounds are discussed.