Studies on gamma-glutamyl transpeptidase of human urine.

A simple and rapid method suitable for clinical laboratories, for the removal of the inhibitors in urine of gamma-glutamyl transpeptidase activity, using an ion-retardation resin, is described. Gel chromatography of urine resulted in appreciable loss of the enzyme activity. Freezing at -5 degrees C and thawing, did not affect the activity of the enzyme. Dimethyl sulfoxide and polyvinyl pyrrolidone up to a creatinine and NaCl at levels found in normal urine did not inhibit the transpeptidase.