<p>3-dehydroquinate dehydratase (<db_xref db="EC" dbkey="4.2.1.10"/>), or dehydroquinase, catalyzes the conversion of 3-dehydroquinate into 3-dehydroshikimate. It is the third step in the shikimate pathway for the biosynthesis of aromatic amino acids from chorismate. Two classes of dehydroquinases exist, known as types I and II.</p><p>The best studied type I enzyme is from <taxon tax_id="562">Escherichia coli</taxon> (gene aroD) and related bacteria where it is a homodimeric protein. In fungi, dehydroquinase is part of a multifunctional enzyme which catalyzes five consecutive steps in the shikimate pathway. A histidine [<cite idref="PUB00002745"/>] is involved in the catalytic mechanism.</p> Dehydroquinase class I