Fig. 4.
Fold of NitN. (A) The fold of the monomer is shown. The visible His tag residues are shown in gray, and the sequence is colored from blue to red. The characteristic αββα fold is clearly seen. (Note that the numbering is displaced by 20 from that given in the PDB code 3hkx deposit to account for the His tag.) (B) Structure of the catalytically active dimer. One monomer is drawn as in panel A, whereas the other highlights the regions of high-temperature factor in pink. The average temperature factor of the Nesterenkonia sp. enzyme is 24, compared to 14 in the case of the PDB code 1j31 enzyme and 9 in the case of the PDB code 2plq enzyme. (C) Stereoview of the catalytic site of NitN. Hydrogen bonding between E41, K111, E119, and Y47 will alter the pKas of the catalytic residues.