Malate dehydrogenase, type 2 <p>Malate dehydrogenases catalyse the interconversion of malate and oxaloacetate using dinucleotide cofactors [<cite idref="PUB00027655"/>]. The enzymes in this entry are found in archaea, bacteria and eukaryotes and fall into two distinct groups. The first group are cytoplamsic, NAD-dependent enzymes which participate in the citric acid cycle (<db_xref db="EC" dbkey="1.1.1.37"/>). The second group are found in plant chloroplasts, use NADP as cofactor, and participate in the C4 cycle (<db_xref db="EC" dbkey="1.1.1.82"/>).</p><p>Structural studies indicate that these enzymes are homodimers with very sinmilar overall topology, though the chloroplast enzymes also have N- and C-terminal extensions, and all contain the classical Rossman fold for NAD(P)H binding [<cite idref="PUB00021232"/>, <cite idref="PUB00023558"/>, <cite idref="PUB00013757"/>, <cite idref="PUB00023967"/>]. Substrate specificity is determined by a mobile loop at the active site which uses charge balancing to discriminate between the correct substrates (malate and oxaloacetate) and other potential oxo/hydroxyacid substrates the enzyme may encounter within the cell [<cite idref="PUB00019781"/>].</p>