GAMMA-GLUTAMYLGLUTAMINE IDENTIFIED IN PLASMA AND CEREBROSPINAL-FLUID FROM HYPERAMMONEMIC PATIENTS

gamma-Glutamylglutamine has been identified in plasma and cerebrospinal fluid. Preparative high voltage electrophoresis was used to isolate the compound from two to three ml of sample. Analysis of archival material from eight patients with urea cycle disorders showed that plasma gamma-glutamylglutamine was 20-214 mu-mol/l when the plasma glutamine was greater than 1000-mu-mol/l and that the relationship was strongly positive (P < 0.0005). Plasma gamma-glutamylglutamine concentration was also raised in one patient with secondary hyperammonaemia, but not in three other cases, one of whom has a plasma glutamine of 10 000-mu-mol/l. Cerebrospinal fluid from the last patient contained 97-mu-mol/l of gamma-glutamylglutamine. Samples of cerebrospinal fluid from two patients with urea cycle disorders were available and the gamma-glutamylglutamine levels were 203 and 313-mu-mol/l. gamma-Glutamylglutamine and 5-oxoproline concentrations were not significantly increased in urine from any of these patients.