Structure of C357U P450cam* in the camphor-bound state. (A)
Active site of the selenoenzyme (yellow) superimposed on that of
P450cam* (green) and WT P450cam (1dz4, gray); all 3 structures
were determined from the monoclinic crystal form. Although the
axial cysteine ligand at position 357 was substituted by
selenocysteine, the structural integrity of the enzyme is
maintained. The increased Fe-Se distance may account for the 2
side chain conformations observed for Leu-358 in the
selenoenzyme. The camphor-binding site is not affected by the
mutations (see Fig. S2). The camphor molecule has been omitted
for clarity. (B) View of the region around Gln-366 in C357U
P450cam* (yellow), P450cam* (green), and the WT protein (gray).
Mutating the native glutamate residue to glutamine induces
displacement of the connected chain of ordered water molecules.