Principle of the Test

Most GGT reagents use the Szasz kinetic method, which involves:

1. Substrate:
   γ-glutamyl-p-nitroanilide
   This compound contains a gamma-glutamyl group.

2. Enzymatic Reaction:
   GGT in the sample transfers the gamma-glutamyl group to an acceptor (often glycylglycine).

3. Product Formation:
   The reaction releases p-nitroaniline, which has a strong yellow color.

4. Measurement:
   The analyzer measures the increase in absorbance at 405 nm.
   The rate of color formation is directly proportional to the GGT activity.

Key Reagent Components

The GGT reagent typically contains:

✔ γ-glutamyl-p-nitroanilide

The chromogenic substrate used in the Szasz method.

✔ Glycylglycine (or similar acceptor)

Accepts the gamma-glutamyl group during the reaction.

✔ Buffers

Maintain optimal pH (usually alkaline, around pH 8.2–8.4).

✔ Stabilizers & Preservatives

Ensure reagent stability and long shelf life.

✔ Detergents / Surfactants

Help maintain reagent clarity and enhance reaction performance.