Test principle
ALT catalyzes the reaction between L-alanine and 2-oxoglutarate. The pyruvate formed is reduced by NADH in a reaction catalyzed by lactate dehydrogenase (LDH) to form L-lactate and NAD+. The rate of the NADH oxidation is directly proportional to the catalytic ALT activity. It is determined by measuring the decrease in absorbance.
L-alanine + α-ketoglutarate > ALT > pyruvate + L-glutamate Pyruvate + NADH + H+ > LDH > L-lactate + NAD+ |