title: Conformational variability of NAD+ in the free and bound states: a nicotinamide sandwich in NAD+ crystals.
abstract: X-ray analysis of the free-acid crystal form of the coenzyme nicotinamide adenine dinucleotide (NAD+) revealed a conformational difference between the free NAD+ molecule and one bound in enzymes or complexed to Li+ ions. The pyrophosphate group showed asymmetry in the phosphate-oxygen bonds of the phosphate-oxygen-phosphate link; this bond at the nicotinamide side of the link is longer than that at the adenosine side by 0.04 angstrom. The crystal structure showed a novel intermolecular stacking of adenine and water molecules on opposite sides of nicotinamide that gives rise to a nicotinamide sandwich.
mesh_terms: D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D000818:Animals; D001411:Geobacillus stearothermophilus / Q000201:enzymology; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008099:Liver / Q000201:enzymology; D008291:Malate Dehydrogenase / Q000378:metabolism; D008958:Models, Molecular; D008968:Molecular Conformation; D009243:NAD / Q000378:metabolism; D008121:Nephropidae; D009536:Niacinamide; D011485:Protein Binding; D014961:X-Ray Diffraction
chemical_list: D009243:NAD; D009536:Niacinamide; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases