This family carries the region of the enzyme trans-2-enoyl-CoA reductase, EC:1.3.1.44, which binds NAD(P)H. The activity of the enzyme was characterised in Euglena where an unusual fatty acid synthesis path-way in the mitochondria performs a malonyl-CoA independent synthesis of fatty acids leading to accumulation of wax esters, which serve as the sink for electrons stemming from glycolytic ATP synthesis and pyruvate oxidation. The full enzyme catalyses the reduction of enoyl-CoA to acyl-CoA. The binding site is conserved as GA/CSpGYG, where p is any polar residue [1].

1: Mitochondrial trans-2-enoyl-CoA reductase of wax ester fermentation from Euglena gracilis defines a new family of enzymes involved in lipid synthesis. Hoffmeister M, Piotrowski M, Nowitzki U, Martin W; J Biol Chem. 2005;280:4329-4338. PMID:15569691