title: Transferred nuclear overhauser effect in nuclear magnetic resonance diffusion measurements of ligand-protein binding.
abstract: The drug discovery process relies on characterizing structure-activity relationships, since specific ligand-target interactions often result in important biological functions. Measuring diffusion coefficients by nuclear magnetic resonance spectroscopy is a useful way to study binding, because changes can be detected when a small ligand interacts with a macromolecular target. Diffusion coefficients can be miscalculated, however, due to magnetization transfer between the receptor and ligand. This transferred nuclear Overhauser effect (trNOE) disrupts the observed signal decay due to diffusion as a function of the experimental diffusion time. Since longer diffusion times also selectively edit free ligand signal, the measured diffusion coefficients become biased toward the fraction of bound ligand. Despite this discrepancy, under these experimental conditions, the trNOE selectively influences the measured signals of binding ligands and can be used to gain insight into ligand-protein interactions. These phenomena have been studied for caffeine and L-tryptophan, which bind to human serum albumin, and the antimalarial agent trimethoprim, which interacts with dihydrofolate reductase. The results provide insight into the nature of ligand-protein binding and are thus useful for elucidating the molecular features of the ligand that interact with the protein.
authors.affiliation: Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Laura H
authors.initials: LH
authors.lastname: Lucas
authors.forename: Jiangli
authors.initials: J
authors.lastname: Yan
authors.forename: Cynthia K
authors.initials: CK
authors.lastname: Larive
authors.forename: Edward R
authors.initials: ER
authors.lastname: Zartler
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Shapiro
mesh_terms: D002110:Caffeine / Q000737:chemistry / Q000378:metabolism; D004058:Diffusion; D006801:Humans; D008024:Ligands; D008280:Magnetics; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D014295:Trimethoprim / Q000737:chemistry / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism
chemical_list: D008024:Ligands; D011506:Proteins; D012709:Serum Albumin; D002110:Caffeine; D014364:Tryptophan; D014295:Trimethoprim; D013762:Tetrahydrofolate Dehydrogenase