title: Use of a copper-chelated lipid speeds up NMR measurements from membrane proteins.
abstract: Recent studies have demonstrated the abilities of solid-state NMR techniques to solve atomic-level-resolution structures and dynamics of membrane-associated proteins and peptides. However, high-throughput applications of solid-state NMR spectroscopy are hampered by long acquisition times due to the low sensitivity of the technique. In this study, we demonstrate the use of a paramagnetic copper-chelated lipid to enhance the spin-lattice relaxation and thereby speed up solid-state NMR measurements. Fluid lamellar-phase bicelles composed of a lipid, detergent, and the copper-chelated lipid and containing a uniformly (15)N-labeled antimicrobial peptide, subtilosin A, were used at room temperature. The use of a chelating lipid reduces the concentration of free copper and limits RF-induced heating, a major problem for fluid samples. Our results demonstrate a 6.2-fold speed increase and a 2.7-fold improvement in signal-to-noise ratio for solid-state NMR experiments under magic-angle spinning and static conditions, respectively. Furthermore, solid-state NMR measurements are shown to be feasible even for nanomole concentrations of a membrane-associated peptide.
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, USA.
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Jiadi
authors.initials: J
authors.lastname: Xu
authors.forename: Karen E
authors.initials: KE
authors.lastname: Kawulka
authors.forename: John C
authors.initials: JC
authors.lastname: Vederas
authors.forename: Ayyalusamy
authors.initials: A
authors.lastname: Ramamoorthy
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008565:Membrane Proteins / Q000737:chemistry*; D013997:Time Factors
chemical_list: D002614:Chelating Agents; D008051:Lipid Bilayers; D008565:Membrane Proteins; D003300:Copper