FIGURE 9.

Structural explanation for why the CTD does not bind NAD⁺. A, a model of NAD⁺ from the GSALDH domain has been docked to the CTD in the canonical position for Rossmann dinucleotide-binding domains. Residues predicted to clash NAD⁺ are in cyan. B, the surface of the CTD where NAD⁺ would be expected to bind. NAD⁺ is docked into the canonical position for Rossmann dinucleotide-binding domains. Note the absence of a well defined pocket for NAD⁺. C, the surface of the bona fide NAD⁺-binding site of the Rossmann 1 domain of SmPutA. Note the presence of a pocket that is complementary in shape to the active conformation of NAD⁺.