PubMed HealthSearch

PubMed · 7583058

Variable-angle double rotation technique: a new two-dimensional high-resolution technique for quadrupolar nuclei.

Abstract

We describe a new two-dimensional high-resolution technique for nuclei with semi-integer spins subjected to strong quadrupole interactions. This variable-angle double rotation (VADOR) technique separates anisotropic spectral patterns according to the isotropic shift of each species. No sudden sample reorientation is needed for VADOR which can consequently be used regardless of the "relaxation times". This technique can also be utilized to characterize slow molecular reorientations in two- or three-dimensional experiments. We also propose a new geometry for DOR probes (theta e = 70.124 degrees, theta i = 54.736 degrees) which suppresses first-order interactions (chemical shift anisotropy and dipolar) more efficiently than the geometry (theta e = 54.736 degrees, theta i = 30.556 degrees) presently employed.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J P Amoureux. 1995. Variable-angle double rotation technique: a new two-dimensional high-resolution technique for quadrupolar nuclei.. https://doi.org/10.1016/0926-2040(95)00008-e

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Measuring column void volumes with NMR.

A novel method for measuring resin porosities and column void volumes with fluorine. NMR has not been developed. In situ measurements of the void volumes accessible to an array of fluorinated probe molecules are used to characterize the pore size distribution of the media. Application of this simple procedure is demonstrated for a commercially packed column and several bulk resins. The porosity distributions obtained by this technique are similar to those obtained by size exclusion chromatography. Unlike chromatographic tracer studies, however, this method does not require packed columns.

Magnetic Resonance Spectroscopy

Reactivity of nitrogen monoxide species with NADH: implications for nitric oxide-dependent posttranslational protein modification.

Nitric oxide (NO.) and NO. donors incite NAD- [i.e., mono(ADP-ribosylation)] and NADH-dependent posttranslational protein modifications by an as yet unknown mechanism. A route of pyridine nucleotide-dependent, NO.-stimulated protein modification has recently been hypothesized [S. Dimmeler, and B. Brune, (1992) Eur. J. Biochem. 210, 305-310; J. S. Stamler (1994) Cell 78, 931-936]. An essential feature of this proposed mechanism is NADH nitrosation, for a nitroso-NADH adduct is considered to be a key reactant in the generation of pyridine nucleotide-modified protein. To evaluate at the molecular level the ability of NADH to act as a nitrosation substrate, the potential effects of NO., the nitrosothiols S-nitrosoglutathione and S-nitrosocysteine, the nitrosating agent tert-butyl-nitrite, and the NO. metabolite peroxynitrite on the molecular and functional (i.e., hydride-transfer) properties of NADH have been directly assessed at physiological pH. Exposure of NADH to NO. or nitrosothiol altered neither the hydride-transfer capability of the pyridine nucleotide nor its ultraviolet spectrum in ways suggestive of NADH nitrosation. As determined by NMR spectroscopy, NADH was refractory to the well-recognized nitrosating agent tert-butyl nitrite. Consequently, it appears that NADH is an unfavorable substrate for nitrosation under physiological conditions. These data are inconsistent with the proposal that NO. or a NO.-derived nitrosating agent interacts with NADH to generate the nitroso-NADH hypothesized to be essential to NO.-stimulated, pyridine nucleotide-dependent protein modification. Peroxynitrite, a possible source of nitrosating compounds, readily oxidized NADH to NAD, but demonstrated no potential to form a nitroso-NADH adduct. The facility with which NADH is oxidized to NAD has implications for peroxynitrite-mediated tissue damage.

Magnetic Resonance Spectroscopy

Structural characterization of three RNA hexanucleotide loops from the internal ribosome entry site of polioviruses.

Structural characteristics of three RNA hairpins from the internal ribosome entry site of poliovirus mRNAs have been determined in solution by NMR. Complete proton, phosphorus and carbon resonance assignments were made for the three 16 nt hairpins. The loop sequences, 5'-AAUCCA , AAACCA and GAACCA, have been shown to be essential for viral mRNA translation. NOESY spectra for the three oligomers were very similar indicating a common three dimensional structure. Stems were A-type duplexes with C3'-endo sugar pucker. In the loops, sequential base stacking interactions were detected for all bases except between U8/A8 and C9, indicating a turn in the phosphodiester backbone at this point. Only one nucleotide, U8/A8, had a sugar pucker which deviated appreciably from C3'-endo. The final base in the loop, A11, exhibited an unusual gauche (-) gamma angle. An ensemble of 10 structures calculated for one hairpin using restrained molecular dynamics shows that the first three bases of the loop are turned so as to be exposed to the exterior of the molecule, while the remaining three bases are in an orientation approximating a continuation of the stem helix. Structure calculations and NMR relaxation measurements indicate that the loop apex is subject to considerable local dynamics.

Magnetic Resonance Spectroscopy