Proton Magnetic Relaxation and Protein Hydration

K.-Daszkiewicz, Olgierd; Hennel, J.W.; Lubas, Barbara; Szczepkowski, T

doi:10.1038/2001006a0

Cited by 119 publications

(46 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Early observations of an enhanced water 1 H relaxation rate in protein solutions were attributed to a few water molecules rigidly bound to (and thus tumbling with) the protein, but exchanging rapidly with the remaining bulk-like water (Daszkiewicz et al 1963). On the basis of relaxation data at two magnetic fields, a three-state model was proposed that also incorporated hydration water with rotational dynamics intermediate between rigidly bound and bulk water (Caputa et al 1967).…”

Section: Magnetic Relaxation As a Probe Of Protein Hydration Dynamicsmentioning

confidence: 99%

Protein hydration dynamics in solution: a critical survey

Halle

2004

Phil. Trans. R. Soc. Lond. B

499

576

View full text Add to dashboard Cite

The properties of water in biological systems have been studied for well over a century by a wide range of physical techniques, but progress has been slow and erratic. Protein hydration-the perturbation of water structure and dynamics by the protein surface-has been a particularly rich source of controversy and confusion. Our aim here is to critically examine central concepts in the description of protein hydration, and to assess the experimental basis for the current view of protein hydration, with the focus on dynamic aspects. Recent oxygen-17 magnetic relaxation dispersion (MRD) experiments have shown that the vast majority of water molecules in the protein hydration layer suffer a mere twofold dynamic retardation compared with bulk water. The high mobility of hydration water ensures that all thermally activated processes at the protein-water interface, such as binding, recognition and catalysis, can proceed at high rates. The MRD-derived picture of a highly mobile hydration layer is consistent with recent molecular dynamics simulations, but is incompatible with results deduced from intermolecular nuclear Overhauser effect spectroscopy, dielectric relaxation and fluorescence spectroscopy. It is also inconsistent with the common view of hydration effects on protein hydrodynamics. Here, we show how these discrepancies can be resolved.

show abstract

Section: Magnetic Relaxation As a Probe Of Protein Hydration Dynamicsmentioning

confidence: 99%

Protein hydration dynamics in solution: a critical survey

Halle

2004

Phil. Trans. R. Soc. Lond. B

499

576

View full text Add to dashboard Cite

show abstract

“…[1][2][3] Nevertheless, an interesting question is why the selective neuronal death and gliosis in the present study appear hyperintense on T1W images and hypointense on T2W MRI. Theoretically, besides intracellular methemoglobin in hemorrhagic tissue, 8 the following factors can shorten the T1 and T2 relaxation times: (1) factors immobilizing water molecules 9 (macromolecular hydration effect), such as a concentrated solution of protein 10 and calcified tissue 11 (surface relaxation mechanism); (2) lipid 9,12 ; and (3) paramagnetic compounds characterized by having at least 1 unpaired orbital electron 13 (paramagnetic proton-electron dipole-dipole interaction), including metal ions (eg, iron, manganese, copper, chromium, cobalt, and gadolinium), 14 molecular oxygen (O 2 ), 15 and free radicals. 16 In the present study, the hyperintensity of DIH did not decline on the FS MRI.…”

Section: Discussionmentioning

confidence: 99%

Novel Brain Ischemic Change on MRI

Fujioka

Taoka

Matsuo

et al. 1999

Stroke

View full text Add to dashboard Cite

Background and Purpose-Specific change of persistent hyperintensity/hypointensity on T1-weighted (T1W) and T2-weighted (T2W) MRI, respectively, has been reported to develop in the human basal ganglia after brief hemispheric ischemia. We investigated whether this ischemic change observed in humans could be reproduced experimentally in rats after brief middle cerebral artery (MCA) occlusion (MCAO), and if so, what the neuroradiological change represented histologically. Methods-The origin of the right MCA of male Wistar rats (nϭ25) was occluded for 15 minutes by inserting a silicon-coated nylon thread from the external carotid artery into the internal carotid artery. After 15 minutes' MCAO, coronal MR images (T1W, T2W, and T1W with fat saturation pulse) were obtained once at 3-day reperfusion (nϭ5) and twice at 3-and 7-day reperfusion (nϭ20). Brain specimens were examined histologically immediately after the last MRI study in all rats. Results-Neither T1W nor T2W MRI showed marked signal changes 3 days after reperfusion following 15-minute MCAO. However, the ischemic change of hyperintensity and hypointensity on T1W and T2W MRI, respectively, appeared in the striatum following 7-day reperfusion after 15-minute MCAO (nϭ19/20). Histological examination revealed that the specific lesion in the rat striatum on MRI corresponded to selective neuronal death and proliferation of reactive astrocytes and microglia without infarct, hemorrhage, lipid accumulation, or calcification. Conclusions-Brief MCAO with reperfusion induces the delayed ischemic changes of hyperintensity and hypointensity on T1W and T2W MRI, respectively, in the rat striatum with high reproducibility. This specific ischemic change on MRI histologically corresponded to selective neuronal death and gliosis with preservation of the macroscopic structure of the brain. A similar MRI pattern reported in patients who have sustained brief ischemia may represent similar histology. We speculate that the ischemic change reflects some biochemical changes affecting the magnetic field as the brain tissue undergoes subtle structural changes.

show abstract

“…This behaviour is described by the Hennel-Daszkiewicz equation. 9 Additionally the measured spin-spin relaxation functions were single-exponential. For BSA concentration higher then 30% the best fits to the measured transverse relaxation were achieved in the form of two exponential components with different relaxation times, T 21 and T 22 (Fig.…”

Section: Resultsmentioning

confidence: 99%