The nucleotide-binding Rossmann fold. The Rossmann fold, a common nucleotide-binding motif, is minimally composed of a β-α-β-α-β motif. This example is from a section of EpiD, a decarboxylase enzyme from the bacterium Staphylococcus epidermis. The β-α-β motifs are connected as shown in the chain topology diagram (bottom). In EpiD, the active-site loop binds a flavin mononucleotide.