L-Malate Dehydrogenase (L-MDH)

The Uses of L-Malate Dehydrogenase (L-MDH)

The enzyme L-malate dehydrogenase from pig heart has been used to measure PEPCK (phosphoenolpyruvate carboxykinase) activity. The oxaloacetate, produced by PEPCK, is reduced to malate via the oxidation of NADH, which in turn is measured at 340 nm using a spectrophotometer. The enzyme has also been used to measure oxaloacetate by measuring the reduction in NADH spectroscopically at 340 nm.

General Description

L-malate:NAD⁺ oxidoreductase
The L-malate dehydrogenase enzyme is a nuclear gene product that is synthesized with a 24-residue amino-terminal signal peptide. This peptide is proteolytically cleaved during the translocation of the enzyme to the mitochondrial matrix.

Biochem/physiol Actions

The enzyme L-malate dehydrogenase from pig heart catalyzes the oxidation of L-malate to oxaloacetate. The enzyme is an NAD-dependent mitochondrial dehydrogenase that functions in the tricarboxylic acid cycle. It is a component of the malate-aspartate shuttle that transports reducing equivalents across the inner mitochondrial membrane in the form of malate.