High-Resolution Magnetic Relaxation Dispersion Measurements of Solute Spin Probes Using a Dual-Magnet System

Wagner, Shawn; Dinesen, T. R. J.; Rayner, Timothy J.; Bryant, Robert G.

doi:10.1006/jmre.1999.1811

Cited by 46 publications

(41 citation statements)

References 20 publications

(16 reference statements)

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“…Notably, the field-shuttling technique cannot be applied for these purposes, as it is limited by the time of sample transfer which does not permit detection of relaxation rates greater than % 20 s À1 . [15,16] The inset in Figure 1 a shows the collective protonmagnetization decay at 0.1 MHz for a solution of lysozyme (2.8 mm, pH* 3.5 in D 2 O; pH* = pH-meter reading in D 2 O solution) previously treated with D 2 O for deuteration at exchangeable-proton positions. For a rigid protein, at all frequencies of interest herein, CH 2 protons relax approximately two to three times faster than CH and nonexchanged NH protons; internal rotation causes CH 3 protons to relax as slowly as CH protons.…”

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confidence: 99%

NMR Spectroscopic Detection of Protein Protons and Longitudinal Relaxation Rates between 0.01 and 50 MHz

et al. 2005

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Nuclear magnetic relaxation data of water nuclei at variable fields provide valuable information on the dynamics of watersolute interactions. [1][2][3] However, information can be collected only within certain field ranges in which the nuclear relaxation rates are field-dependent owing to the dispersion of the spectral density, J(w,t). The dispersion depends on the type of motion and on the observed nucleus. The most informative 1 H NMR spectroscopic frequency range for rotational motions is centered around 10 MHz for small proteins (M W % 10 4 Da) and smaller frequencies for larger proteins and protein aggregates. Of course, resolution is low at these fields and in practice only one signal (or an unresolved signal envelope) can be detected. Furthermore, only the abundant water protons can be conveniently studied under such low sensitivity.Relaxation of the isotopes 17 O and 2 H in enriched water can also be studied; [1] in these cases the centers of the informative field ranges increase by a factor % 7 with respect to 1 H as a result of the magnetogyric ratios of 17 O and 2 H. Because water interacts with proteins, such relaxation studies provide direct information on the nature of water-protein dynamics, but give only indirect information on the protein itself.[4-6] It would be highly desirable to have complementary information directly from the protons of the protein, but this has been impractical so far owing to the low sensitivity of the available instrumentation. Protein 1 H relaxation data have been reported only on protein solutions of concentrations ! 35 % by mass, [7,8] far from physiological conditions. Improvements in field-cycling technology [9][10][11][12] have led to the production of instrumentation [13] with a % 10-fold increase in the signal-to-noise ratio, [14] with which direct protein 1 H detection can be attempted for protein concen- Figure 1. Protein 1 H relaxation dispersions for lysozyme solutions (2.8 mm in D 2 O) at a) pH* 3.5, and b) pH* 9.0 (pH=pH-meter reading in D20 solution). The time decay of the collective protein 1 H magnetization at 0.1 MHz and its single-exponential fit are shown in the inset of part a). Theoretical relaxation rates were obtained through singleexponential fits of time decays of collective protein 1 H magnetization calculated from the known protein structure of lysozyme [17] and a complete relaxation matrix (CORMA) analysis.[18] Only exchangeable NH protons from secondary structure elements ( % 50 % of total) were included, whereas all other exchangeable proton positions were assumed to be deuterated. Inclusion of either all or none of the NH protons affected the calculated rates by AE 2 %. The theoretical lowfield hE 2 i values obtained in this way were used to fit Equation (1) to the data (solid lines). The dotted lines represent data fits with two J-(w,t) terms in Equation (1) ( Table 1). Panel c) shows the protein 1 H relaxation dispersion for a solution of a-synuclein in D 2 O (1.4 mm, pH* 7.1). The solid and dotted lines represent fits with one or two J-(...

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NMR Spectroscopic Detection of Protein Protons and Longitudinal Relaxation Rates between 0.01 and 50 MHz

et al. 2005

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“…However, Wagner et al 3 have developed a method for sealing samples free of bubbles, which can probably be adapted to our shuttle configuration. They have used this method for many useful research projects at room temperature.…”

Section: Sample Containmentmentioning

confidence: 99%

“…The possible applications for such a device far exceed the measurement of relaxation, 1,3,6 and proton Nuclear Overhauser Effect (NOE), 2 and includes enhancement of heteronuclear overhauser effects, of nuclear relaxation from engineered spin labels in proteins, and of cross-correlation effects for R 1 in certain cases. We believe that a very large number of applications will be found in the study of protein ligands in fast dissociative exchange, on the ligated R 1 time scale, with solvent.…”

Section: Introductionmentioning

confidence: 99%

“…To our knowledge, there was only one operating high-resolution shuttling spectrometer in the world when we started this project, and the approach and intent was somewhat different than ours. 3 A shuttling probe has also been described and used extensively for photochemically induced dynamic nuclear polarization studies, in which the entire probe, specially rebuilt, is moved in and out of the magnet, using a stepper motor and belt drive, while spinning the sample. 4,5 For these reasons we decided to see how easily a pneumatic device could be built and what it could do.…”

Section: Introductionmentioning

confidence: 99%

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Shuttling device for high‐resolution measurements of relaxation and related phenomena in solution at low field, using a shared commercial 500 MHz NMR instrument

Redfield

2003

Magnetic Reson in Chemistry

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An apparatus is described that can pneumatically move an aqueous liquid NMR sample sealed in a 5 or 8 mm standard tube, from the center of a standard Varian 500 MHz spectrometer and probe out to any position in its fringe field, and back, under computer control. Applications to low-field relaxation and other measurements are discussed briefly, particularly using 31 P, and 15 N and 13 C with proton detection, utilizing the full power of the commercial system for preparation before, and detection after, a relaxation or mixing interval at low field. Transverse relaxation, polarization transfer, and other transverse manipulations are virtually impossible with this apparatus while the sample is at the low (fringe) field, because of the tremendous inhomogeneity of that field. The spectrometer and probe are unmodified commercial products and the apparatus is expected to be usable in any other system or field without much modification. The apparatus is wheeled to the instrument and installed, and later removed without trace, in less than 1 h each way, including a probe change. A pneumatic glass shuttle tube, 22 mm inside diameter, held in an aluminum support tube, is temporarily inserted in place of the upper tube that is supplied by the manufacturer to be inserted into the top of the magnet. A standard thin-walled NMR tube is connected to a plastic piston shuttle that is moved up or down inside the shuttle tube, by low vacuum or pressure applied from the top. The low value of magnetic field, where the relaxation process measured occurs, is determined by a movable mechanical stop whose position is changed manually between runs. The downward path is initiated by a short higher pressure pulse, followed by a long lower pressure interval. The round trip time limit is about 0.2 s, suitable for relaxation rate measurements in the range up to about 10 s −1 .Variable-temperature operation uses the regulator of the host instrument. After an overview, a detailed description of all aspects of construction and use is provided. The shuttling apparatus itself is relatively straightforward, but development of a simple sample confinement method was difficult, as expected. Problems of bubble formation and of denaturation of a protein are partly solved, and sample loading and sealing is easy. Pulse programs for this apparatus are easily generated from otherwise standard pulse sequences by addition of a few simple instructions. Operation does not require any special knowledge, nor much extra training. A major result of our program is to show that the sensitivity using such a shuttle can be that of the host instrument, not affected by such possible problems as vibration, and only reduced by the predictable losses due to relaxation during the 200-300 ms round trip shuttle time, and the inability to utilize solvent flipback methods.

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“…Of course further optimization could be achieved by investigating both the materials and production techniques (roughness and ellipticity) of the tube. Besides aliphatic polyamides (Nylon) 6 , other good candidates for cartridge material are, for instance, the polyoxymethylene (Delrin) 3 and polychlorotrifluoroethylene (kel-F) 16 , all of which were used successfully in the similar setups cited, having been chosen for their mechanical strength.…”

Section: Shuttlementioning

confidence: 99%

Note: A fast pneumatic sample-shuttle with attenuated shocks

Biancalana

Dancheva

Stiaccini

2014

Review of Scientific Instruments

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We describe a home-built pneumatic shuttle suitable for the fast displacement of samples in the vicinity of a highly sensitive atomic magnetometer. The samples are magnetized at 1 T using a Halbach assembly of magnets. The device enables the remote detection of free induction decay in ultra-low-field and zero-field NMR experiments, in relaxometric measurements and in other applications involving the displacement of magnetized samples within time intervals as short as a few tens of milliseconds. Other possible applications of fast sample shuttling exist in radiological studies, where samples have to be irradiated and then analyzed in a cold environment.

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High-Resolution Magnetic Relaxation Dispersion Measurements of Solute Spin Probes Using a Dual-Magnet System

Cited by 46 publications

References 20 publications

NMR Spectroscopic Detection of Protein Protons and Longitudinal Relaxation Rates between 0.01 and 50 MHz

NMR Spectroscopic Detection of Protein Protons and Longitudinal Relaxation Rates between 0.01 and 50 MHz

Shuttling device for high‐resolution measurements of relaxation and related phenomena in solution at low field, using a shared commercial 500 MHz NMR instrument

Note: A fast pneumatic sample-shuttle with attenuated shocks

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