X-ray crystal structures of VioC complexes revealing changes in the conformation
of the substrate/product side chain through the reaction cycle.
A, Reactant complex with Fe(II)
(orange), 2OG
(yellow), and L-hArg
(pink). B,
Complex with vanadium [cyan; (hydr)oxo
shown in red], succinate
(purple), and L-hArg
(pink). C,
Complex after exposure of crystals of the reactant complex to O2
showing electron density consistent with formation of
(3S)-OH-L-hArg (green) (color
coding of other ligands as in A). In all
structures, a 2Fo-Fc electron density map for
selected active site components is shown in black mesh and contoured to 1.5
σ.