Comparison of FAOX-II and MSOX actives sites. A, FSA bound
to FAOX-II. B, methyl-thioacetate (MTA) bound to MSOX.
His-269 in MSOX and Glu-280 in FAOX-II bind to the fructosamine hydroxyl
groups. The Arg-52–Tyr-55—Lys-348 triad in MSOX and the
Tyr-60–Arg-112–Lys-368 triad in FAOX-II interact with the
inhibitor carboxylate. C, FAOX-II hydrophobic pocket. Met-98 and
Phe-258 undergo slight rearrangement upon FSA binding (light magenta
in free FAOX-II, dark magenta in the ligand-bound structure).
D, FAOX-II active site accessibility. The molecular surface of the
inhibitor-bound FAOX-II structure is shown with the two flexible active site
loops computationally removed. The FAD cofactor and FSA inhibitor are shown as
beige and green space-filling spheres, respectively. With
the flexible loops removed, both FAD and FSA are partially accessible to
solvent and about 12 Å from the opening of the active site.