ALT catalyses the transformation of L-Alanin and 2-Oxoglutarate at optimalpH. The Pyruvate released in the reaction is transformed by Lactate dehydrogenase (LDH) in the presence of NADH /NAD+ coenzyme to L- lactate, while the NADH/NAD+ oxidoreductive process shows a decrease in absorbance at 340 nm. The change in absorbance correlates with serum ALT activity.