engleski

Determining the Orientation of Drugs in Receptors by Solvent Paramagnetic Relaxation NMR spectroscopy

A detailed knowledge of receptor-ligand interactions is important in the process of rational drug design. NMR spectroscopy is often employed for screening compound libraries and, in cases of weak ligand-receptor interactions, for the determination of binding epitopes. Here we present a new solution state NMR approach for obtaining the orientation of a drug in a receptor. Upon the addition of an inert paramagnetic agent to the solvent, relaxation enhancements on ligand nuclei depend on the insertion depth in the protein. If the ligand is in fast exchange between the free and bound state, these solvent paramagnetic relaxation enhancements (solvent PREs) are partly transferred to the free ligand where they can be observed with high resolution and without any size limitation of the receptor. The information obtained about the orientation of the ligand with respect to the receptor could be used for guiding docking calculations, provided that the three-dimensional atomic resolution structure of the receptor is available. Identifying which parts of a drug are buried deepest in the receptor can provide clues about the site on the ligand where chemical modification most likely results in an altered binding strength. Solvent PREs have also been used to study the binding and orientation of macrolide antibiotics to membrane mimetics. These studies could rationalize a side effect of macrolide antibiotics- phospholipidosis. Macrolide antibiotics induce phospholipidosis by reducing the activity of phospholipase A1 towards phosphatidylcholine in membranes. Our results indicate that macrolides inhibit this function via reducing the amount of free phosphatidylcholine through membrane binding.

NMR; paramagnetic relaxation; drugs; receptors

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