Residual dipolar couplings applications

Other exciting applications involved using parallel tempering in connection with available experimental data. For example, Falcioni and Deem [57] used X-ray data to refine structures of zeolites, and Haliloglu et al. [58] refined NMR structural data for proteins (in particular using residual dipolar coupling constraints). 

Multidimensional NMR spectroscopy proves to be a powerful method to reveal structural and dynamical information at the molecular level in elastomers. Residual dipolar couplings can be measured site-selectively and correlated with the crosslink density and mechanical stress. The local segmental order and information on local molecular motions can be also obtained with newly developed 2D NMR methods. The information at the molecular level can be correlated with macroscopic properties of elastomers and provides the basis for a better design of material properties for specific applications. 

Cierpicki T, Liang B, Tamm LK, Bushweller JH. Increasing the accuracy of solution NMR structures of membrane proteins by application of residual dipolar couplings. High-resolution structure of outer membrane protein A. J. Am. Chem. Soc. 2006 128 6947-6951. 

Almond et investigated how aqueous dynamical simulations of flexible molecules can be compared against NMR data. The methodology compares state-of-the-art NMR residual dipolar coupling, NOESY and relaxation, to molecular dynamics simulations in water over several nanoseconds. In contrast to many previous applications of residual dipolar couplings in structure investigation of biomolecules, the approach described here uses MD simulations to provide a dynamic representation of the molecules. 

While methods of spectrum analysis capable of super-resolution exist, that is, methods that can achieve resolution greater than l/Wx, the most common of these, linear prediction (LP) extrapolation, has substantial drawbacks. LP extrapolation is used to extrapolate signals beyond the measured interval. While this can dramatically suppress truncation artifacts associated with zero-filling as well as improve resolution, because LP extrapolation implicitly assumes exponential decay it can lead to subtle frequency bias when the signal decay is not perfectly exponential [8]. This bias can have detrimental consequences for applications that require the determination of small fi-equency differences, such as measurement of residual dipolar couplings (RDCs). 

R 320 H. M. Al-Hashimi and A. Gorin, Application of NMR Residual Dipolar Couplings in Studies of RNA Towards High-Throughput Investigations , Appl. Genom. Proteom., 2003,2, 3... 

Kramer and Glaser analysed the transfer efficiency of cross-relaxation compensated (Clean) TOCSY sequences for applications to residual dipolar couplings. Surprisingly most conventional Clean TOCSY sequences are very inefficient for dipolar transfer. It is shown theoretically, that this is a general property of all phase-alternating mixing sequences, i.e., for such sequences the suppression of cross-relaxation excludes dipolar transfer in the spin-diffusion limit. A new family of clean dipolar TOCSY sequences is derived which provides excellent transfer efficiencies for a broad range of offset frequencies. 

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