title: Accurate measurements of ¹³C-¹³C distances in uniformly ¹³C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy.
abstract: Application of sets of (13)C-(13)C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important (13)C-(13)C distances in uniformly (13)C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl ((13)C') and aliphatic ((13)C(aliphatic)) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly (13)C,(15)N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of (13)C'-(13)C(aliphatic) distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform (13)C,(15)N-labeling on the FGAIL fragment.
authors.affiliation: Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Lasse Arnt
authors.initials: LA
authors.lastname: Straasø
authors.affiliation: Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Jakob Toudahl
authors.initials: JT
authors.lastname: Nielsen
authors.affiliation: Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Bjerring
authors.affiliation: Division of Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Navin
authors.initials: N
authors.lastname: Khaneja
authors.affiliation: Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Niels Chr
authors.initials: NC
authors.lastname: Nielsen
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011506:Proteins / Q000737:chemistry*
chemical_list: D002247:Carbon Isotopes; D011506:Proteins