Home  About us  Contact
 

High-resolution NMR (high-resolution + nmr)

Distribution by Scientific Domains
Chemistry80%

Terms modified by High-resolution NMR

  • high-resolution nmr spectrum
    		•

    Selected Abstracts

    Studying natural structural protein fibers by solid-state nuclear magnetic resonance

    CONCEPTS IN MAGNETIC RESONANCE, Issue 1 2009
    Alexandre A. Arnold
    Abstract As a consequence of evolutionary pressure, various organisms have developed structural fibers displaying a range of exceptional mechanical properties adapted specifically to their functions. An understanding of these properties at the molecular level requires a detailed description of local structure, orientation with respect to the fiber and size of constitutive units, and dynamics on various timescales. The size and lack of long-range order in these protein systems constitute an important challenge to classical structural techniques such as high-resolution NMR and X-ray diffraction. Solid-state NMR overcomes these constraints and is uniquely suited to the study of these inherently disordered systems. Solid-state NMR experiments developed or applied to determine structure, orientation, and dynamics of these complex proteins will be reviewed and illustrated through examples of their applications to fibers such as spider and silkworm silks, collagen, elastin, and keratin. © 2009 Wiley Periodicals, Inc. Concepts Magn Reson Part A 34A: 24,27, 2009. [source]

    Probing residue-specific interactions in the stabilization of proteins using high-resolution NMR: A study of disulfide bond compensation

    JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2010
    Andria L. Skinner
    Abstract It is well established that the oxidation state of cysteine residues in proteins is critical to overall physical stability. Disulfide bonds most often impart thermodynamic stability, but in some cases, diminish it. Predicting the circumstances that lead to each outcome is difficult because mechanistic information is lacking. Because the techniques typically used to study protein stability do not provide sufficient detail, high-resolution NMR was used in combination with low-resolution analysis to obtain mechanistic information regarding disulfide bond formation in a model protein. Tm (CD) and Tonset (SLS) for the reduced and oxidized wild type and C104S and C49S mutants were measured. The mutant proteins have altered Tms and Tonsets compared to the reduced wild type, indicating that differences in local interactions of the Cys side chains are important for stability. The NMR spectra clearly show distinct differences in the chemical environment surrounding these Cys residues and the overall tertiary structure. The C49S protein, which is less stable and more aggregation prone than reduced wild type, lacks a hydrogen bond between Y53 and H103. Increased flexibility of the Y53-containing loop is correlated with increased dynamics and unraveling of ,2, which likely leads to edge strand initiated aggregation of the central ,-sheet. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2643,2654, 2010 [source]

    Structure determination of slowly exchanging conformers in solution using high-resolution NMR, computational modeling and DFT-GIAO chemical shielding: application to an erythronolide A derivative

    MAGNETIC RESONANCE IN CHEMISTRY, Issue 11 2009
    Dieter Muri
    Abstract We discuss and demonstrate the potential of HSQC-TOCSY and HSQC-NOESY experiments to offer solutions for overlap problems in COSY and NOESY spectra, leading to improved signals that can be unambiguously assigned to individual carbons. Direct comparison of experimental 1H and 13C chemical shielding with density functional theory (DFT)-calculated values are uninformative; in contrast, the relative differences in experimental shielding between pairs of molecules correlates well with the relative differences in DFT-GIAO shielding for the computed lowest energy conformers. A detailed application of both experimental and theoretical techniques is illustrated for slowly exchanging conformers of an erythronolide A derivative, which demonstrates that structure determination can strongly benefit from the interplay between experiment and theory. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Inherently Chiral Molecular Clips: Synthesis, Chiroptical Properties, and Application to Chiral Discrimination

    CHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2007
    Gaku Fukuhara
    Abstract Inherently chiral molecular clips (MCs), pseudoenantiomeric anti - 1 and anti - 2, as well as mesoid syn - 3, were synthesized by diastereodifferentiating repetitive Diels,Alder reactions of the achiral bisdienophile 6 with chiral diene 5 generated in situ from (,)-menthyl 3,4-bis(dibromomethyl)benzoate 4. These MCs were successfully separated by chiral HPLC to give optically active anti - 1 and anti - 2 and almost optically inactive syn - 3. The structures of anti - 1, anti - 2, and syn - 3 were assigned by high-resolution NMR and the absolute configurations of anti - 1 and anti - 2 were determined by the exciton-chirality method. Optically active anti - 2 can serve as a chiral host. It binds the HCl adduct of D -tryptophan methyl ester (D -TrpOMe,HCl) 3.5,times stronger than the L -enantiomer (KD/KL=3.5). [source]