Fig. 2

Crystal structure of a 2HADH from Sinorhizobium meliloti (PDB ID: 5v7n) complexed with a cofactor (NADP⁺) and a reaction product (2-keto-D-gluconic acid). Cofactor-binding and substrate-binding domains are indicated by brackets. a, Secondary structure elements are labeled; the other subunit of the dimer is translucent. b, Highly conserved residues (> 90% in all 2HADH sequences) are labeled