title: Determination of the binding epitope of lidocaine with AGP: minimizing the effects of nonspecific binding in saturation transfer difference experiments.
abstract: The ligand epitope map and the effect of nonspecific binding is assessed for lidocaine binding to α(1)-acid glycoprotein using the saturation transfer difference nuclear magnetic resonance experiment performed as a function of the ligand/protein ratio. The experimental design tested two different approaches for preparing solutions with various ligand/protein ratios; holding the protein concentration constant and increasing the ligand concentration; and holding the ligand concentration constant while decreasing the protein concentration. Nonspecific binding effects were more prevalent in experiments in which the ligand concentration was increased, although spectra with higher signal-to-noise ratios were obtained under these conditions. The epitope map determined for achiral lidocaine is compared with previously determined results for the (R)- and (S)-enantiomers of propranolol. The weaker binding affinity of lidocaine may be partially attributed to steric hindrance by the lidocaine N-ethyl groups which may prevent close contact of the lidocaine amine with the negatively charged amino acids at the apex of the protein binding pocket.
authors: Department of Chemistry, University of California, Riverside, CA 92521, USA.
authors: Jennifer R
authors: JR
authors: Cruz
authors: Cynthia K
authors: CK
authors: Larive
mesh_terms: D001665:Binding Sites; D007700:Kinetics; D008012:Lidocaine / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D009961:Orosomucoid / Q000737:chemistry*; D011485:Protein Binding
chemical_list: D009961:Orosomucoid; D008012:Lidocaine