Resolution NMR studies

Void RR, Prosser RS, Deese AJ (1997) Isotropic solutions of phospholipid bicelles a new membrane mimetic for high-resolution NMR studies of polypeptides. J Biomol NMR 9 329-335... 

We report herein on high-resolution NMR studies of cuticles from limes (7) and of suberized cell walls from potatoes. Measurements include identification and quantitation of magnetically distinct carbon moieties, determination of site-specific polymer dynamics on both MHz and kHz timescales, and delineation of the interactions among polyester, wax, and cell-wall components. 

Moulthrop, J. S., Swatloski, R. R, Moyna, G. et al.. High-resolution NMR studies of cellulose and cellulose oligomers in ionic liquid solutions, Chem. Commun., 1557,2005. 

The anisotropic nature of the dipolar, quadrupolar and chemical shift anisotropy interactions requires that the isotropy of molecular orientation relative to the applied magnetic field be broken in order to allow their direct observation in terms of shifts in the frequencies of resonances.20,32,38 40 For high resolution NMR studies this has meant, thus far, that some degree of alignment of the molecule needs to be established. Almost all molecules will align to a small extent due to the anisotropy of their magnetic... 

High resolution NMR studies, in combination with molecular mechanics, were performed to unequivocally assign the prochiral P-protons for the phenylalanine sidechain and to define the shape of the sweet receptor [49], The previous assignment [48] of the NMR signals for the P-protons of phenylalanine was shown to be in error. 

Finally, the application of optimal control theory to DNP studies needs to be discussed. Optimal control theory is a means to systematically design and optimize pulse sequences to maximize the efficiency of transfer between spin states. While this method was initially introduced to benefit high-resolution NMR studies, it has recently been adapted to improve the electron-nuclear polarization transfer in DNP applications by considering simple two- or three-spin systems. " While no experimental implementation of DNP pulse sequences designed by optimal control methods has been reported, these methods have the great potential to enhance DNP performance at X-band, due to the powerful pulsed ESR hardware that is commercially available at these frequencies. 

Elastomeric poly acetaldehyde is amorphous and atactic. High resolution NMR studies were carried out in order to determine the actual tacticity of the polymer (4, 5, 23). Poly acetaldehyde consists mainly of heterotactic sequences isotactic sequences are also present in the polymer. The ratio of heterotactic to isotactic varies, but it is usually between 2-3 1. A detailed description of the tacticity determination by high resolution NMR will be given in a subsequent paper by Goodman and Brandrup (23). 

The slow electron relaxation rates of copper(II) ions were expected to broaden the NMR lines of nearby nuclei beyond detection, and high-resolution NMR studies on blue Cu(II) sites were considered unfeasible for a long time. However, when the H NMR spectra of oxidized forms from Thi. versutus and azurin from Ps. aeruginosa were recorded for the hrst time, relatively weU-resolved lines could be observed (Kalverda et al., 1996). 

Kakalis, L.T., Kumosinski, T.F., and Farrell, H.M. (1990). A multinuclear, high-resolution NMR study of bovine casein micelles and submicelles. Biophys. Chem. 38, 87-98. 

In liquid-state NMR, spin relaxation due to cross-correlation of two anisotropic spin interactions can provide useful information about molecular structure and dynamics. These effects are manifest as differential line widths or line intensities in the NMR spectra. Recently, new experiments were developed for the accurate measurement of numerous cross-correlated relaxation rates in scalar coupled multi-spin systems. The recently introduced concept of transverse relaxation optimized spectroscopy (TROSY) is also based on cross-correlated relaxation. Brutscher outlined the basic concepts and experimental techniques necessary for understanding and exploiting cross-correlated relaxation effects in macromolecules. In addition, he presented some examples showing the potential of cross-correlated relaxation for high-resolution NMR studies of proteins and nucleic acids. 

More recent work utilized the shuttling ONP apparatus to perform enhanced, high-resolution NMR studies of the acridine-doped fluorene system. The pulse sequence detailing the relative timing of the various (optical, rf, and static) applied fields is shown in Fig. 4(b). As before, ONP was performed at low field (but without an rf driving field)... 

Over its nearly 40-year history, ONP has permitted a wide range of novel photochemical and photophysical experiments in various aromatic molecular crystals unfortunately, this approach has not yet seen significant application beyond such fundamental studies in these systems. However, tantalizing recent results - particularly (1) the observation of extremely high polarization values under modest experimental conditions (2) the transfer of high polarization to rare nuclei for enhanced, high-resolution NMR studies ... 

Orita, M., Nishikawa, F., Kohno, T., Senda, T., Mitsui, Y., Yaeta, E., Kazunari, T. and Nishikawa, S. (1996) High-resolution NMR study of a GdAGA tetranucleotide loop that is an improved substrate for ricin, a cytotoxic plant protein. Nucleic Acids Res, 24, 611-618. 

Recently, high resolution NMR studies of solids have been realized by using advanced pulse and mechanical techniques, and so have provided a variety of structural and dynamic information about polymer systems. Further, it can be said that solid state NMR has provided characteristic information that cannot be obtained by other spectroscopic methods, and that it has become a very powerful means for elucidating the structure and dynamics of polymer systems. 

This enzyme catalyzes a reaction that appears to be very homologous to that of pyruvate kinase. One similarity other than the proposed mechanism is that this enzyme also requires two cations to elicit the most active form of the enzyme. Although calculations of kinetic activation data indicate that both GDP and metal-GDP (and GTP and metal-GTP) can both serve as substrates for the enzyme, the function of GDPrree as substrate has not been demonstrated, and if so, the metal-GDP complex is the more active form (79). Unlike pyruvate kinase, this enzyme does not require a monovalent cation. Kinetic activation studies indicate that the enzyme-bound metal facilitates the interaction of the substrates phosphoenolpyruvate and nucleotide with the enzyme, but not the substrate CO2. High-resolution NMR studies of both phosphoenolpyruvate and the nucleotide have demonstrated that in contrast to the classic case of pyruvate kinase, the substrates appear to bind in the second coordination sphere of the bound cation. These results indicate a much different role in the activation processes. The activation appears to be modulated by metal-bound water molecules. This interaction appears to be with both the phosphate of phosphoenolpyruvate (80) and the y-phosphate of GTP (79) [as indicated in Fig. 6 (80).] Thus, in the activation of phosphoenolpyruvate, the metal must increase the cationic character of the water molecule with which the phosphate of the substrate interacts. 

Coster, D., Blumenfeld, A. L., and Fripiat, J. J. 1994. Lewis acid sites and surface aluminum in aluminas and zeolites a high-resolution NMR study. /. Phys. Chem. 98 6201-6211. 

Nicholson J K, Buckingham M J, Sadler P J (1983). High resolution NMR studies... 

Shenkarev ZO, Lyukmanova EN, Paramonov AS, Shingarova LN, Chupin VV, Kirpichnikov MP, Blommers MJ, Arseniev AS (2010) Lipid-protein nanodiscs as reference medium in detergent screening for high-resolution NMR studies of integral membrane proteins. J Am Chem Soc 132 5628-5629... 

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