In enzymology, a malate dehydrogenase (quinone) (), formerly malate dehydrogenase (acceptor) (EC 1.1.99.16), is an enzyme that catalyzes the chemical reaction (S)-malate + a quinone oxaloacetate + reduced quinone Thus, the two substrates of this enzyme are (S)-malate and a quinone, whereas its two products are oxaloacetate and reduced quinone. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with a quinone as acceptor. The systematic name of this enzyme class is (S)-malate:quinone oxidoreductase. Other names in common use include FAD-dependent malate-vitamin K reductase, malate-vitamin K reductase, and (S)-malate:(quinone) oxidoreductase. This enzyme participates in pyruvate metabolism. It employs one cofactor, FAD. References EC 1.1.5 Flavoproteins Enzymes of unknown structure