Statin inhibition of HMG-CoA reductase: a 3-dimensional view.

Statins act by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and thereby reducing cholesterol synthesis. In X-ray crystallographic studies, we have determined the structures of the catalytic portions of the enzyme in complex with statin molecules. These studies show that the HMG-like moiety of statin molecules occupy the HMG binding site of the enzyme, with the hydrophobic groups of the statins occupying a binding site exposed by movement of flexible helices in the enzyme catalytic domain. In addition to bonds formed by the HMG-like moiety, statins exhibit different types and numbers of binding interactions in association with structural differences. Type 1 statins (e.g., simvastatin) exhibit binding via a decalin ring structure, and type 2 statins (e.g., rosuvastatin, atorvastatin, fluvastatin) exhibit additional binding via their fluorophenyl group. Rosuvastatin and atorvastatin exhibit hydrogen bonds absent from other type 2 statins; rosuvastatin exhibits a unique bond via its electronegative sulfone group. Differences in statin structure and binding characteristics may partially contribute to differences in potency of HMG-CoA reductase inhibition and other pharmacologic properties.