Malic enzyme

Malic enzyme (EC 1.1.1.39), not to be confused with Malate dehydrogenase, is an enzyme that catalyzes the chemical reaction

(S)-malate + NADP⁺ pyruvate + CO₂ + NADPH

Thus, the two substrates of this enzyme are (S)-malate and NADP⁺, whereas its three products are pyruvate, CO₂, and NADPH.

This enzyme belongs to the family of oxidoreductases, to be specific, those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (S)-malate:NADP+ oxidoreductase (decarboxylating). Other names in common use include malic enzyme, pyruvic-malic carboxylase, NADP+-specific malic enzyme, and NADP+-malic enzyme. This enzyme participates in pyruvate metabolism and carbon fixation.

Malic enzyme is commonly confused with another malate oxidoreductase named malate dehydrogenase (MDH) (EC 1.1.1.37). MDH is used reversibly in the conversion of malate to oxaloacetate and involves NAD⁺/NADH instead of NADP⁺/NADPH

Structural studies

As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes 1DO8, 1EFK, 1EFL, 1PJ2, 1PJ3, 1PJ4, and 1QR6.

References

• Saz HJ and Hubbard JA (1957). "The oxidative decarboxylation of malate by Ascaris lumbricoides". J. Biol. Chem. 225: 921–933. PMID 13416294.