<p> Fumarase C catalyzes the stereospecific interconversion of fumarate to L-malate as part of the metabolic citric acid or Kreb's cycle. The recent three-dimensional structure of fumarase C from <taxon tax_id="562">Escherichia coli</taxon> has identified a binding site for anions which is generated by side chains from three of the four subunits within the tetramer. These same side chains are found in the three most highly conserved regions within the class II fumarate hydratase family. Putative fumarases from several species (<taxon tax_id="1773">Mycobacterium tuberculosis</taxon>, <taxon tax_id="1902">Streptomyces coelicolor</taxon>, <taxon tax_id="287">Pseudomonas aeruginosa</taxon>) branch deeply, although within the same branch of a phylogenetic tree rooted by aspartate ammonia-lyase sequences.</p> Fumarate hydratase, class II