title: Study of Small-Molecule-Membrane Protein Binding Kinetics with Nanodisc and Charge-Sensitive Optical Detection.
abstract: Nanodisc technology provides membrane proteins with a nativelike lipid bilayer and much-needed solubility and enables in vitro quantification of membrane protein binding with ligands. However, it has been a challenge to measure interaction between small-molecule ligands and nanodisc-encapsulated membrane proteins, because the responses of traditional mass-based detection methods scale with the mass of the ligands. We have developed a charge-sensitive optical detection (CSOD) method for label-free measurement of the binding kinetics of low molecular mass ligands with nanodisc-encapsulated membrane proteins. This microplate-compatible method is sensitive to the charge instead of the mass of a ligand and is able to measure both large and small molecules in a potentially high-throughput format. Using CSOD, we measured the binding kinetics between peptide and small-molecule ligands and a nanodisc-encapsulated potassium ion channel protein, KcsA-Kv1.3. Both association and dissociation rate constants for these ligands are obtained for the first time. The CSOD results were validated by the consistency of the values with reported binding affinities. In addition, we found that CSOD can tolerate up to 3.9% dimethyl sulfoxide (DMSO) and up to 10% serum, which shows its compatibility with realistic sample conditions.
authors.affiliation: Department of Chemistry and Biochemistry, Arizona State University , Tempe, Arizona 85281, United States.
authors.forename: Guangzhong
authors.initials: G
authors.lastname: Ma
authors.forename: Yan
authors.initials: Y
authors.lastname: Guan
authors.forename: Shaopeng
authors.initials: S
authors.lastname: Wang
authors.affiliation: Therapeutic Discovery, Amgen Incorporated , Thousand Oaks, California 91320, United States.
authors.forename: Han
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Chemistry and Biochemistry, Arizona State University , Tempe, Arizona 85281, United States.
authors.forename: Nongjian
authors.initials: N
authors.lastname: Tao
mesh_terms: D000818:Animals; D001665:Binding Sites; D006736:Horses; D007700:Kinetics; D051664:Kv1.3 Potassium Channel / Q000737:chemistry*; D008024:Ligands; D049329:Nanostructures / Q000737:chemistry*; D055095:Optics and Photonics / Q000379:methods*; D011485:Protein Binding; D054852:Small Molecule Libraries / Q000737:chemistry*
chemical_list: D051664:Kv1.3 Potassium Channel; D008024:Ligands; D054852:Small Molecule Libraries