Accurate measurements of ¹³C-¹³C distances in uniformly ¹³C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

• Published in: The Journal of chemical physics 2014-09, Vol.141 (11), p.114201-114201
• Main Authors: Straasø, Lasse Arnt, Nielsen, Jakob Toudahl, Bjerring, Morten, Khaneja, Navin, Nielsen, Niels Chr
• Format: Article
• Language: English
• Subjects: Carbon 13; Carbon Isotopes - chemistry; Magnetic Resonance Spectroscopy - methods; NMR spectroscopy; Proteins; Proteins - chemistry
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.4895527

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.