FIG 4.
Substrate-binding pocket in chain C of the F275W derivative of CARDO (Oxy) complexed with FN overlaid on terminal Oxy structures. The mononuclear iron is shown as a brown sphere. (a) Overlaid structures of the F275W derivative (cyan) with CAR (green) (PDB accession no. 4NBD) and WT Oxy (white) with CAR (yellow) (PDB accession no. 2DE7). The electron density (1.0 σ 2Fo-Fc) of CAR in the F275W derivative is shown as a black wire mesh. The distances between the carbonyl oxygen of Gly178 and the imino nitrogen of CAR in the WT and the F275W derivative are orange and green (inset), respectively. (b) Overlaid structures of the F275W derivative (cyan) with FN (green) and WT Oxy (white) with CAR (yellow). The electron density (1.0 σ 2Fo-Fc) of FN in the F275W derivative is shown as a black wire mesh. The direction of C-9 of FN was the opposite of that of the imino nitrogen of CAR, which forms a hydrogen bond with the carbonyl oxygen of Gly178 in WT Oxy complexed with bound CAR.