NAD+
NAD+-enzyme binding mode and structure, overview. The NAD+-binding pocket is constituted by seven loops (beta7-alpha4, beta8-alpha5, beta10-alpha7, beta11-beta12, alpha8-beta13, alpha9-alpha10, and alpha11-beta16) and four alpha-helices (alpha4, alpha6, alpha7, and alpha10). The adenine ring is stabilized in the hydrophobic pocket that is formed by Phe151, Pro211, Ala212, Phe229, Val235 and Leu239, and a hydrogen bond with Ser215 also contributes to the binding of the ring. Residues Lys178, Glu181, and Pro211 constitute a suitable space for binding of the ribose ring, and stabilize the 2'-hydroxyl-group of the ring. The formation of the ribose ring binding site does not seem to be large enough to accommodate the phosphorylated ribose ring. Therefore the enzyme shows poor activity with NADP+ as a cofactor. The diphosphate moiety is stabilized by residues Asn331, Arg333, and Arg334 through directly and water-mediated hydrogen bond networks. Residues Arg334 and Glu384 stabilize the ribose moiety of NAD+, and the nicotinamide ring is stabilized by residues Gln160 and Glu253 by hydrogen bonding
