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A Spin System Labeled and Highly Resolved ed-H(CCO)NH-TOCSY Experiment for the Facilitated Assignment of Proton Side Chains in Partially Deuterated Samples (1998)

Gschwind, Ruth M. ; Gemmecker, Gerd ; Kessler, Horst

Springer

Journal of biomolecular NMR 11 (1998), S. 191-198

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ISSN: 1573-5001

Keywords: multi-quantum ; partially deuterated proteins ; proton side-chain assignment ; spin system editing

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology

Notes: Abstract The introduction of deuterated and partially deuterated protein samples has greatly facilitated the 13C assignment of larger proteins. Here we present a new version of the HC(CO)NH-TOCSY experiment, the ed-H(CCO)NH-TOCSY experiment for partially deuterated samples, introducing a multi-quantum proton evolution period. This approach removes the main relaxation source (the dipolar coupling to the directly bound 13C spin) and leads to a significant reduction of the proton and carbon relaxation rates. Thus, the indirect proton dimension can be acquired with high resolution, combined with a phase labeling of the proton resonances according to the C-C spin system topology. This editing scheme, independent of the CHn multiplicity, allows to distinguish between proton side-chain positions occurring within a narrow chemical shift range. Therefore this new experiment facilitates the assignment of the proton chemical shifts of partially deuterated samples even of high molecular weights, as demonstrated on a 31 kDa protein.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1008233703362

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Scalar Coupling Constants - Their Analysis and Their Application for the Elucidation of StructuresDedicated to Professor Richard R. Ernst (1995)

Eberstadt, Matthias ; Gemmecker, Gerd ; Mierke, Dale F. ; [et al.]

Weinheim : Wiley-Blackwell

Angewandte Chemie International Edition in English 34 (1995), S. 1671-1695

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ISSN: 0570-0833

Keywords: NMR spectroscopy ; structure elucidation ; Coupling constants ; NMR spectroscopy ; Structure elucidation ; Chemistry ; General Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Since their discovery in the early fifties, scalar/coupling constants have been of great interest to the NMR spectroscopist. Their impact on structure determination by NMR spectroscopy is founded on the fact that the size of the coupling constant is directly related to molecular conformation. Today, for most chemical substances the parameters for the Karplus relationship, which relates the vicinial (3-bond) coupling constant to the dihedral angle, have been determined. In addition to proton-proton distances, the application of coupling constants in modern conformational analysis is indispensable. In the study of larger molecules which are of current interest, more and more involved experiments are necessary in order to overcome signal overlap and increasing line widths. A large number of experimental techniques for the determination of coupling constants has been developed; however, for this reason the choice of the most appropriate experiment to use has become more difficult. This decision must be made carefully to maximize instrument usage and obtain the largest number of couplings with the greatest accuracy possible. Many of the computer programs used in structure calculations can directly apply coupling constant restraints, similar to proton-proton distances developed from NOEs. Therefore, not only is the quality of the structure improved, but the molecular motions (internal dynamics) are better described. In this article, we review the techniques that exist today with particular attention paid to helping the non-expert to choose the appropriate experiment for the problem at hand. In addition, the use of coupling constants in computer simulations are discussed.

Additional Material: 32 Ill.