Deuteron Magnetic Resonance Study of Cupric Sulfate Pentahydrate

Soda, Gen; Chiba, Takehiko

doi:10.1063/1.1670818

Cited by 202 publications

(94 citation statements)

References 48 publications

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“…The splitting of the doublet clearly narrowed to 30 kHz, however, suggesting that the methyl axis now has an orientational fluctuation. In a two-site jump model, this 7-kHz narrowing requires a fluctuation of the methyl axis over an angle of +30" (Soda & Chiba, 1969). Granted that hydration induces a native conformation in SSI, the above observation suggests that smallamplitude motions are present in the side chains of methionines 70 and 73 in the S1 and/or S4 pockets of the enzyme.…”

Section: Significance Of the Internal Motions Of The Met Side Chains mentioning

confidence: 94%

Dynamics of the three methionyl side chains of Streptomyces subtilisin inhibitor. Deuterium NMR studies in solution and in the solid state

et al. 1996

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Streptomyces subtilisin inhibitor (SSI) contains three methionine residues in a subunit: two (at positions 73 and 70) in the crucial enzyme-recognition sites P1 and P4, respectively, and one (Met 103) in the hydrophobic core.The motions of the side chains of these three Met residues and the changes in mobility on binding with subtilisin were studied by deuterium NMR spectroscopy in solution and in crystalline and powder solids. For this purpose, the wild-type SSI was deuterium-labeled at the methyl groups of all three Met residues, and three artificial mutant proteins were labeled at only one specific Met methyl group each. In solution, for methionines 73 and 70, the effective correlation times were only 0.8-1.0 x 10"'s indicating that the two side chains on the surface fluctuate almost freely. On formation of a complex with subtilisin, however, these high mobilities were quenched, giving a correlation time of 1.1 x s for the side chains of methionines 70 and 73. The correlation time of Met 103, located in the hydrophobic core, was at least 1.0 X lo-* s in free SSI, showing that its side chain motion is highly restricted. The nature of the internal motions of the three Met side chains was examined in more detail by deuterium NMR spectroscopy of powder and crystalline samples. The spectral patterns of the powder samples depended critically on hydration: immediately after lyophilization, the side-chain motions of the three Met residues were nearly quenched. With gradual hydration to 0.20 gram of water per gram protein-water, the orientational fluctuation of the methyl axes of methionines 70 and 73 was selectively enhanced in both amplitude and frequency (to about 1 MHz) and, at nearly saturating hydration (0.60 gram of water per gram protein-water), became extremely high in amplitude and frequency (> 10 MHz). In contrast, the polycrystalline wild-type SSI spectrum showed fine structures, reflecting characteristic motions of the Met side chains. The polycrystalline spectrum could be reproduced reasonably well by the same motion models and parameters used to simulate the powder spectrum at the final level of hydration, suggesting that the side-chain motions are similar in the fully hydrated powder and in crystals. Spin-lattice relaxation measurements gave evidence that, even in crystals, the methyl axes of all three Met residues undergo rapid motions with correlation times between IO-' and lO"'s, comparable to the correlation times in solution. Finally, in the hydrated stoichiometric complex of SSI with subtilisin BPN' in the solid state, large-amplitude motions are absent, but the side chains of methionines 7 0 and/or 73 are likely to have small-amplitude motions.Keywords: deuterium NMR; methionyl side chain dynamics; hydration of solid proteins; protein internal motion; specific deuteration; Streptomyces subtilisin inhibitor

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Section: Significance Of the Internal Motions Of The Met Side Chains mentioning

confidence: 94%

Dynamics of the three methionyl side chains of Streptomyces subtilisin inhibitor. Deuterium NMR studies in solution and in the solid state

et al. 1996

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“…In this case, Sinnecker et al (21,22,24) have shown that the point dipole model does not work due to the increased covalent character of the H-bond that is not covered in the point dipole approximation. A more reliable alternative approach is to evaluate H-bond distances from the nuclear quadrupole coupling constant of 2 H. As empirically proposed by Soda and Chiba (25) where a and b are empirical parameters (22). Using a ϭ 319 kHz and b ϭ 607 kHz Å 3 (20) and the value of ϭ 176 Ϯ 4 kHz deduced from our work, we obtain from Equation 2 a bond length of r(O-2 H) ϭ 1.62 Ϯ 0.02 Å.…”

Section: Table 1 Hyperfine Tensors Derived From Contour Line Shape Anmentioning

confidence: 99%

Determination of the Proton Environment of High Stability Menasemiquinone Intermediate in Escherichia coli Nitrate Reductase A by Pulsed EPR

Grimaldi¹,

Arias-Cartin²,

Lanciano³

et al. 2012

Journal of Biological Chemistry

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Background: Escherichia coli nitrate reductase A highly stabilizes a semiquinone catalytic intermediate. Results:Three proton hyperfine couplings to this radical with atypical characteristics are characterized. Conclusion: Semiquinone binding is strongly asymmetric and occurs via a single short in-plane H-bond. Significance: Learning how the protein environment tunes the semiquinone properties is crucial for understanding the quinol utilization mechanism by energy-transducing enzymes.

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“…Alternatively, the larger peak-to-peak splittings observed for the ammonium-labelled (MA),TeBr, could imply that its static value of the quadrupolar coupling constant, X , is larger than for (CD,NH,+),TeBr,. This second explanation is less likely, since it has been determined (22,23) nium groups continue. That is, the motion of the C-N axis in solid I1 is highly hindered relative to that in the solid I phase.…”

mentioning

confidence: 96%

Nuclear magnetic resonance studies of the methylammonium hexahalotellurates

MacIntosh¹,

Gruwel²,

Robertson³

et al. 1992

Can. J. Chem.

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. Can. J. Chem. 70, 849 (1992).A ' H and NMR study of the solid methylammonium hexahalotellurates, (MA),TeX6 (MA = C H 3~D 3 + or CD3NH3+, X = C1, Br, and I), has been undertaken to characterize the dynamics of the methylammonium (MA) ion as a function of temperature. At room temperature, the MA ion in the hexachlorotellurate (solid 11) is confined to C3 jumps about the C-N axis while a small angle libration of the C-N axis is occurring. In the room temperature phase, solid I, of (MA),TeBr6 and (MA),Te16 the MA ions are performing overall reorientations on the ps time scale, averaging the 'H nuclear quadrupolar interactions to zero. Variable temperature 'H NMR spin-lattice relaxation times, T I , indicate an activation energy, EA, for u i~~t r~p i c n reorientations of the CH3ND3+ ion of 5.2 ? 0.5 and 2.6 ? 0.3 kJ mol-I for X = Br and I, respectively. Deuterium TI values for C-deuterated MA ion in the hexaiodotellurate indicate an E, for whole-ion reorientation of 3.1 + 0.3 kJ mol-'. At any given temperature, the correlation time, T,, derived from the TI results was found to be the same for the two deuterium-labelled hexaiodotellurates. The similarity of both the E, and the T, values implies correlated motion of the methyl and ammonium groups. The ' 4~ TI results for solid I of (MA),Te16 indicate that C-N axis motions, with an EA = 5.6 + 0.6 kJ mol-', are more hindered than N-D or C-D bond dynamics. The ' H NMR spectra for (MA),Te16 (solid 11) and (MA),TeBr6 (solids 11, 111, and IV) are characterized by a Pake doublet line shape. The measured peak-to-peak splittings are less than what is predicted by C3 motion about the molecular symmetry axis. It is possible to model these line shapes by postulating that C3 rotations of the methyl and ammonium groups occur as the C-N axis librates in an effective cone about the position of the static molecular axis. For (CH3ND3),TeBr6 and (CD3NH3),TeBr6 the peak-to-peak splittings in the 'H NMR spectra were measured as a function of temperature in solid phases 11, 111, and IV and were found to be similar. Finally, the 'H NMR line shape relaxation for (MA)'TeBr6 (solid 111) displays an orientation dependence indicating that rotations about the C-N axis are discrete rather than diffusive in nature. For solid phase I1 of (MA),TeC16, the line shape is observed to relax isotropically, implying that continuous C3 rotations are taking place. Les couplages entre sommets qui ont etC mesurCes sont plus faibles que ceux que l'on peut prCdire sur la base du mouvement C3 autour de l'axe de symCtrie molCculaire. I1 est possible de crCer un modkle de la forme de ces raies en faisant I'hypothkse que les rotations C3 des groupes methyle et ammonium se produisent alors que l'axe C-N est en libration dans un cBne effectif autour de la position de l'axe molCculaire statique. Pour les sels (CH3ND3),TeBr6 et (CD3NH3)TeBr6, on a mesurk les couplages entre somrnets dans les spectres Rh4N du 'H, dCterminCs en fonction de la tem+rature, pour les phases 11, III et IV; on a trouvC qu'ils sont semblables....

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Deuteron Magnetic Resonance Study of Cupric Sulfate Pentahydrate

Cited by 202 publications

References 48 publications

Dynamics of the three methionyl side chains of Streptomyces subtilisin inhibitor. Deuterium NMR studies in solution and in the solid state

Dynamics of the three methionyl side chains of Streptomyces subtilisin inhibitor. Deuterium NMR studies in solution and in the solid state

Determination of the Proton Environment of High Stability Menasemiquinone Intermediate in Escherichia coli Nitrate Reductase A by Pulsed EPR

Nuclear magnetic resonance studies of the methylammonium hexahalotellurates

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