The Gamma-GlutamylTransferase (GGT; EC 2.3.2.2) is an enzyme that transfers gamma-glutamyl functional groups. It is found in many tissues, the most notable one being the liver, and has significance in medicine as a diagnostic marker. BioVision's Gamma-GlutamylTransferase Assay Kit provides a convenient tool for sensitive detection of the GGT in a variety of samples. The GGT in sample will recognize L-γ-Glutamyl-pNA as a specific substrate leading to proportional color development. The activity of GGT can be easily quantified colorimetrically (λ = 418 nm). This assay detects GGT activity as low as 0.5 mIU.