title: Selectively dispersed isotope labeling for protein structure determination by magic angle spinning NMR.
abstract: The power of nuclear magnetic resonance spectroscopy derives from its site-specific access to chemical, structural and dynamic information. However, the corresponding multiplicity of interactions can be difficult to tease apart. Complimentary approaches involve spectral editing on the one hand and selective isotope substitution on the other. Here we present a new "redox" approach to the latter: acetate is chosen as the sole carbon source for the extreme oxidation numbers of its two carbons. Consistent with conventional anabolic pathways for the amino acids, [1-(13)C] acetate does not label α carbons, labels other aliphatic carbons and the aromatic carbons very selectively, and labels the carboxyl carbons heavily. The benefits of this labeling scheme are exemplified by magic angle spinning spectra of microcrystalline immunoglobulin binding protein G (GB1): the elimination of most J-couplings and one- and two-bond dipolar couplings provides narrow signals and long-range, intra- and inter-residue, recoupling essential for distance constraints. Inverse redox labeling, from [2-(13)C] acetate, is also expected to be useful: although it retains one-bond couplings in the sidechains, the removal of CA-CO coupling in the backbone should improve the resolution of NCACX spectra.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Eddy
authors.forename: Marina
authors.initials: M
authors.lastname: Belenky
authors.forename: Astrid C
authors.initials: AC
authors.lastname: Sivertsen
authors.forename: Robert G
authors.initials: RG
authors.lastname: Griffin
authors.forename: Judith
authors.initials: J
authors.lastname: Herzfeld
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D003460:Crystallization; D007553:Isotope Labeling; D013058:Mass Spectrometry; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D010461:Peptones; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus; D010461:Peptones