The Expert Panel of Enzymes, International Federation of Clinical Chemistry has published its recommendations for the measurement of serum ALT. The Synermed® method for measuring ALT activity in serum is based upon these recommendations.
The alanine aminotransferase in the sample catalyzes the transfer of the amino group from alanine to alpha-ketoglutarate to form pyruvate and glutamate.
L-alanine + α-ketoglutarate -> pyruvate + glutamate
The pyruvate is reduced to lactate in the presence of lactate dehydrogenase [LDH] with the concurrent oxidation of reduced nicotinamide adenine dinucleotide [NADH] to nicotinamide adenine dinucleotide [NAD].
pyruvate + NADH -> lactate + NAD
The resulting rate of decrease in absorbance at 340 nm is directly proportional to the ALT activity in the sample.