Fig. 4: Structural basis of substrate specificity of the synthetase domain.
From: Different ways to transport ammonia in human and Mycobacterium tuberculosis NAD+ synthetases
a, b Binding of the NaAD+ (yellow stick, a) and sulfonamide derivative 1 (light green stick, SFI, b) in NaAD+-binding site of hsNadE and tbNadE, respectively. c, d Binding of the AMP, MgPPi (green/orange stick, green sphere) in hsNadE (c) and SFI, PPi in tbNadE (d). Cl− atom hydrogen bonds to Mg2+ is in red sphere. In the tbNadE–SFI complex, the first SFI molecule is bound in the NaAD+-binding site (b) and the second SFI together with PPi is bound in the ATP-binding site (d) in a similar manner than the synthetase intermediate analog. This results in the ordering of the P2 loop (pink residues).
