Two-dimensional nmr time evolution correlation spectroscopy in wet lysozyme

Peemoeller, H.; Shenoy, R. K.; Pintar, M. M.

doi:10.1016/0022-2364(81)90116-5

Cited by 41 publications

(56 citation statements)

References 23 publications

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“…This is not surprising in light of earlier work (15) that developed the fast-exchange two-state model, which assumes water in two distinct states. Water bound to larger molecules will have a short T1 since the energy of the excited spins can be more readily coupled to the surrounding lattice.…”

Section: Resultsmentioning

confidence: 83%

See 1 more Smart Citation

Magnetic resonance microscopy of changes in water content in stems of transpiring plants.

Johnson¹,

Brown²,

Kramer³

1987

Proc. Natl. Acad. Sci. U.S.A.

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Differences in water content and degree of binding in the various stem tissues of Pelargonium hortorum were observed by magnetic resonance imaging. 'H images were obtained with a resolution of 100 ,um in the transverse plane and a slice thickness of 1250 pum. It was possible to distinguish the principal tissues of the stem by differences in their proton density or apparent water content and spin lattice relaxation time (T,) or degree of water binding. Measurements were made while the plant was slowly and actively transpiring. In the slowly transpiring plant, T, of various tissues ranged from an average of 659 to 865 ms with a proton density variation offrom 72 to 100%. In the actively transpiring plant, T, ranged from an average of 511 to 736 ms, and the proton density was reduced, ranging between 62 and 88% of the peak value found in the slowly transpiring plant. The fibrous sheath surrounding the vascular tissue and the epidermal region was found to have the highest spin density and T1. This paper describes an investigation of the use of magnetic resonance imaging (MRI) for nondestructive research on the content and binding of water in plant tissues. Since the initial demonstration of spatially localized magnetic resonance by Lauterbur (1), it has been clear that MRI has potential as a valuable tool in the study ofplants. Several early researchers demonstrated images of fruits and nuts (2-4), and MRI has been applied to studies of intact plants (5, 6). Studies have been limited by picture volume elements (voxels) with sampling volumes of >10 mm3. But the resolution has been extended into the microscopic domain with voxels as small as 0.012 mm3 with a sufficiently high signal to noise ratio to distinguish subtle differences in signal intensity (7-11). This permits production of images that distinguish the various tissues in a plant stem.A magnetic resonance image is generated by placing a sample in a strong magnetic field that causes the protons (primarily in water) to precess synchronously about the field at the Larmor frequency. Externally applied radio frequency pulses at the Larmor frequency can be used to manipulate the precessing protons away from their equilibrium position (precessing about the field). In the process the protons absorb energy that is later reemitted. The reemitted signal can be localized in space to create a digital image by application of magnetic gradients. For the partial saturation or the spin echo sequence (12), the signal S at any point in the image is given by Eq. 1 as S = NO41 -2e(-TR-TE/2)/T1 + e-TRIT1ie-TE/T2[1]where TR is the repetition time between pulse sequences, TE is the time between the 900 radio frequency pulse and the formation of the spin echo signal, NH is the proton density, and T1 and T2 are the spin lattice and spin-spin relaxation times of the sample. For a more complete description of the technology see ref. 13. One application of MRI in plant science would be to monitor water movement through plant tissue, using change in NH as a gauge of water content...

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Section: Resultsmentioning

confidence: 83%

“…1. T1 is inversely correlated with the fraction of the water that is bound, i.e., water that is hydrogen bonded to larger macromolecules for a period comparable to T1 (14,15). It was in fact the observation ofprolonged T1 in tumors that provided much of the early impetus for the development of MRI for clinical uses (16).…”

Section: Introductionmentioning

confidence: 99%

Magnetic resonance microscopy of changes in water content in stems of transpiring plants.

Johnson¹,

Brown²,

Kramer³

1987

Proc. Natl. Acad. Sci. U.S.A.

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“…The worst case is if some of the protein protons are magnetically isolated either because of rapid local motions decoupling the dipole-dipole interaction, or because of the folding of the protein providing a spatially isolated proton or groups of protons. We have no evidence that this is a significant problem, though Peemoeller and collaborators (26) have raised this concern some time ago.…”

Section: Dependence On Cross-linking Agent Concentrationmentioning

confidence: 94%

Magnetization transfer, cross‐relaxation, and chemical exchange in rotationally immobilized protein gels

Zhou

Bryant

1994

Magnetic Resonance in Med

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Water proton spin-lattice relaxation rates are reported as a function of the magnetic field strength for cross-linked bovine serum albumin samples. The relaxation dispersion profile is analyzed using a relaxation model where the solid components have the magnetic field dependence proportional to v-0.5 which may result from a defect diffusion model with two degrees of freedom. If the cross-linking agent concentration is not sufficiently high, the relaxation dispersion curve may have significant contributions from freely rotating protein. The magnetic field dependence of the relaxation rates studied as a function of the proton mole fraction in the sample show that approximately 30% of the magnetization transfer rate is directly proportional to the proton mole fraction. This contribution is identified with the magnetization transfer from exchange of whole water molecules with buried binding sites on the protein. The second order magnetization transfer rate constant is 388 s-1 assuming unit water spin concentration. The solid component relaxation obeys an Arrhenius activation law, but the overall temperature dependence of the cross-relaxation is complicated by chemical exchange processes which enter with opposite sign.

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“…This form of two-dimensional time evolution (2DTE) correlation spectroscopy, is called two-dimensional time domain (2DTD) NMR [30,31]. It involves the reconstruction of the free induction decays (FIDs) of the various magnetization components of the system from correlated spin-lattice relaxation measurements.…”

Section: Measurementsmentioning

confidence: 99%

Proton and Deuteron Relaxation Study of Molecular Dynamics in Lysozyme Solutions

et al. 2000

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A nuclear magnetic resonance spin-lattice relaxation dispersion study of the relaxation of several magnetization components in both natural and deuterated lysozyme solutions was undertaken at 20°C. Proton and deuteron resonances were employed. The two-dimensional time evolution of the magnetization and the spin-spin relaxation were analyzed. In addition, an isotopic dilution study was performed at 5 and 30.6 MHz. The results indicate that the water proton spin-lattice relaxation rate which arises from intermolecular relaxation between the water protons and the lysozyme protons represents a relatively strong relaxation mechanism. A model for the dynamics of the water molecules, consistent with the proton and deuteron dispersions as well as with the isotopic dilution results, is presented.

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Two-dimensional nmr time evolution correlation spectroscopy in wet lysozyme

Cited by 41 publications

References 23 publications

Magnetic resonance microscopy of changes in water content in stems of transpiring plants.

Magnetic resonance microscopy of changes in water content in stems of transpiring plants.

Magnetization transfer, cross‐relaxation, and chemical exchange in rotationally immobilized protein gels

Proton and Deuteron Relaxation Study of Molecular Dynamics in Lysozyme Solutions

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