Figure 3.

Active-site interactions in the WT NMNAT–NADP⁺ complex. (a) Ribbon diagram of NMNAT with helices shown in green and strands in yellow. The molecule of NADP⁺ is shown in ball-and-stick representation. (b) Interacting NMNAT residues and NADP⁺ are shown in ball-and-stick representation. The most notable interactions are between the 2′-phosphate of NADP⁺ and NMNAT residues His16 and His19. The NADP⁺ adenine ring also stacks with the side chain of Tyr126. (c) Schematic representation of the interactions between WT NMNAT and NADP⁺. The distances and identities of the polar interactions are shown and are described in the text. Identical interactions occur between Arg11Lys and Arg47Glu NMNAT with NADP⁺ but have not been shown.