Lipoxygenases are non-heme iron enzymes, which catalyze the stereo- and regiospecific
hydroperoxidation of unsaturated fatty acids. Spectroscopic studies on soybean lipoxygenase have shown
that the ferrous form of the enzyme is a mixture of five- and six-coordinate species (40 and 60%,
respectively). Addition of substrate leads to a purely six-coordinate form. A series of mutations in the
second coordination sphere (Q697E, Q697N, Q495A, and Q495E) were generated, and the structures of
the mutants were solved by crystallography [Tomchick et al. (2001) Biochemistry 40, 7509-7517]. While
this study clearly showed the contribution of H-bond interactions between the first and the second
coordination spheres in catalysis, no correlation with the coordination environment of the FeII was observed.
A recent study using density-functional theory [Lehnert and Solomon (2002) J. Biol. Inorg. Chem. 8,
294-305] indicated that coordination flexibility, involving the Asn694 ligand, is regulated via ...