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| In the last step of the citric acid cycle, malate (C4O5H4) is oxidized to oxaloacetate (C4O5H2) by malate dehydrogenase. | ||||||||||||||||||
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| The reaction yields a NADH molecule which is equivalent to 3 ATP. It's the fourth coenzyme reduced through the oxidation of a single acetate unit.
Beside the production of NADH from NAD+, the oxidation of malate produces oxaloacetate which is an important intermediate in several biosynthetic processes. |
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| In eukaryotic cells, two forms of malate dehydrogenase are present. One form is found in the cytosol where it participates in the malate/aspartate shuttle. The other is found in the mitochondria and is a principal enzyme of the citric acid cycle. This web site focuses on the mitochondrial malate dehydrogenase (mMDH).
Although mMDH is found in the mitochondria, it is a nuclear gene product. It is synthesized with a 24-residue amino-terminal transit peptide which is cleaved upon translocation of the enzyme to the mitochondrial matrix. |
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