TROSY optimized spectroscopy

The cross-correlation effects between the DD and CSA interactions also influence the transverse relaxation and lead to the phenomenon known as differential line broadening in a doublet [40], cf Figure Bl.13.8. There is a recent experiment, designed for protein studies, that I wish to mention at tire end of this section. It has been proposed by Pervushin etal [4T], is called TROSY (transverse relaxation optimized spectroscopy) and... 

SQ TOCSY TROSY ZQ ZQC single quantum total correlation spectroscopy transverse relaxation-optimized spectroscopy zero quantum zero-quantum coherence... 

New techniques for data analysis and improvements in instrumentation have now made it possible to carry out stmctural and conformational studies of biopolymers including proteins, polysaccharides, and nucleic acids. NMR, which may be done on noncrystalline materials in solution, provides a technique complementary to X-ray diffraction, which requires crystals for analysis. One-dimensional NMR, as described to this point, can offer structural data for smaller molecules. But proteins and other biopolymers with large numbers of protons will yield a very crowded spectrum with many overlapping lines. In multidimensional NMR (2-D, 3-D, 4-D), peaks are spread out through two or more axes to improve resolution. The techniques of correlation spectroscopy (COSY), nuclear Overhausser effect spectroscopy (NOESY), and transverse relaxation-optimized spectroscopy (TROSY) depend on the observation that nonequivalent protons interact with each other. By using multiple-pulse techniques, it is possible to perturb one nucleus and observe the effect on the spin states of other nuclei. The availability of powerful computers and Fourier transform (FT) calculations makes it possible to elucidate structures of proteins up to 40,000 daltons in molecular mass and there is future promise for studies on proteins over 100,000... 

TNO—Netherlands Organisation for Applied Scientific Research TROSY—transverse relaxation-optimized spectroscopy... 

Thus we cannot escape the depressing reality that 7 2 will get shorter and linewidth will get bigger as we increase the size of the protein studied. The reduced T2 is not only a problem for linewidth, but also causes loss of sensitivity as coherence decays during the defocusing and refocusing delays (1/(2J)) required for INEPT transfer in our 2D experiments. The only ray of hope comes in the form of a new technique called TROSY (transverse relaxation optimized spectroscopy), which takes advantage of the cancellation of dipole-dipole relaxation by CSA relaxation to get an effectively much longer 7 2 value we will briefly discuss TROSY at the end of this chapter. 

NEW TECHNIQUES FOR PROTEIN NMR RESIDUAL DIPOLAR COUPLINGS AND TRANSVERSE RELAXATION OPTIMIZED SPECTROSCOPY (TROSY)... 

A number of recently developed methods offer the potential for improving the quality of NMR structures and for increasing the size of proteins that will be examined. In particular, the use of residual dipolar couplings and of anisotropic contributions to relaxation provide new kinds of restraints that promise to lead to more accurate NMR structures.78 80 The recently developed TROSY (transverse relaxation optimized spectroscopy) method81 exploits relaxation phenomena to produce spectra with narrow lines, and promises to significantly expand the size of protein targets that can be examined by NMR from the current limit of 35 kDa to perhaps 150 kDa. 

R487 K. Pervushin, Imapct of Transverse Ralaxation Optimized Spectroscopy (TROSY) on NMR as a Technique in Structural Biology , Q. Rev. Biophys., 2000, 33, 161... 

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. 

Transverse Relaxation Optimized Spectroscopy (TROSY). - TROSY and CRINEPT are new techniques for solution NMR studies of molecular and supramolecular structures. They allow the collection of high-resolution spectra of structures with molecular weights >100 kDa, significantly extending the range of macromolecular systems that can be studied by NMR in solution. TROSY has already been used to map protein-protein interfaces, to conduct structural studies on membrane proteins and to study nucleic acid conformations in multimolecular assemblies. A number of reviews have been published this year that cover the TROSY technique since its inception. ... 

The most important recent advance of the solution NMR pulse sequence methodology is transverse relaxation optimized spectroscopy (TROSY) due to its significant sensitivity enhancement for large proteins by increasing the lifetimes of NMR signals.17 120 124-126... 

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