Abstract: Elevation of Gamma-Glutamyltransferase (GGT) activity has been implicated in many pathologies and clinical inhibitors of GGT are under development for use in the treatment of liver, cancer, bone and other diseases. In this study, researchers try to find other new inhibitor of GGT researchers used new polar amino acid (threonine) as inhibitor, kinetic studies provide insight into the mechanism of inhibition. New uncompetitive inhibitors of physiological GGT reaction researchers found, development of new inhibitors is essential for exploiting GGT as a therapeutic target. L-threonine, in the presence study was detected as uncompetitive inhibitor, Km values were determined; researchers characterized the kinetic properties of GGT under a standard set of condition. Serum GGT was analyzed in healthy cases (normal 25: mean±SD) age 30±12 years (16.71±0.87), the mean values of GGT levels were statistically significantly higher in liver syndrome (70.79±1.24) and this values decreased in the presence of inhibitor to 60.82±0.87.