1.1.1.B52 | purified recombinant His-tagged enzyme, enzyme AtQR and 2 mM NADH are crystallized from a reservoir solution containing of 0.2 M ammonium acetate, 0.1 M HEPES, pH 8.5, and 24% w/v PEG 3350, X-ray diffraction structure determination and analysis at 1.72 A resolution. Three NADH-bound protomers and one NADH-free protomer form a tetrameric structure in an asymmetric unit of crystals. NADH not only acts as a proton donor, but also contributes to the stability of the alpha7 helix. Molecular replacement using structure of meso-2,3-butanediol dehydrogenase, PDB ID 1GEG, from Klebsiella pneumoniae as template |