This family consists of the C terminal region of several bacterial fumarate hydratase proteins (FumA and FumB). Fumarase, or fumarate hydratase (EC 4.2.1.2), is a component of the citric acid cycle. In facultative anaerobes such as Escherichia coli, fumarase also engages in the reductive pathway from oxaloacetate to succinate during anaerobic growth [1].

1: Oxygen- and growth rate-dependent regulation of Escherichia coli fumarase (FumA, FumB, and FumC) activity. Tseng CP, Yu CC, Lin HH, Chang CY, Kuo JT; J Bacteriol 2001;183:461-467. PMID:11133938