Methyl reorientation in polycrystalline amino acids and peptides: a deuteron NMR spin-lattice relaxation study

Batchelder, Lynne S.; Niu, Chien‐Hua; Torchia, Dennis A.

doi:10.1021/ja00346a021

Cited by 140 publications

(167 citation statements)

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“…When the temperature is further decreased to <260 K, the free rotation around the P-O bonds is quenched and only bond librations persist (58). These data show that at <250 K, dipolar spin diffusion remains the predominant mechanism of magnetization exchange, and at the same time fast rotation of the CF 3 group makes all three fluorine atoms magnetically equivalent (59). Fig.…”

Section: Solid-state Nmr Spectroscopy Of An Alm Oligomermentioning

confidence: 71%

Alamethicin Supramolecular Organization in Lipid Membranes from 19F Solid-State NMR

Salnikov

Raya

Zotti

et al. 2016

Biophysical Journal

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Alamethicins (ALMs) are antimicrobial peptides of fungal origin. Their sequences are rich in hydrophobic amino acids and strongly interact with lipid membranes, where they cause a well-defined increase in conductivity. Therefore, the peptides are thought to form transmembrane helical bundles in which the more hydrophilic residues line a water-filled pore. Whereas the peptide has been well characterized in terms of secondary structure, membrane topology, and interactions, much fewer data are available regarding the quaternary arrangement of the helices within lipid bilayers. A new, to our knowledge, fluorine-labeled ALM derivative was prepared and characterized when reconstituted into phospholipid bilayers. As a part of these studies, C 19 F 3 -labeled compounds were characterized and calibrated for the first time, to our knowledge, for 19 F solid-state NMR distance and oligomerization measurements by centerband-only detection of exchange (CODEX) experiments, which opens up a large range of potential labeling schemes. The 19 F-19 F CODEX solid-state NMR experiments performed with ALM in POPC lipid bilayers and at peptide/lipid ratios of 1:13 are in excellent agreement with molecular-dynamics calculations of dynamic pentameric assemblies. When the peptide/lipid ratio was lowered to 1:30, ALM was found in the dimeric form, indicating that the supramolecular organization is tuned by equilibria that can be shifted by changes in environmental conditions.

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Section: Solid-state Nmr Spectroscopy Of An Alm Oligomermentioning

confidence: 71%

Alamethicin Supramolecular Organization in Lipid Membranes from 19F Solid-State NMR

Salnikov

Raya

Zotti

et al. 2016

Biophysical Journal

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“…At temperatures above the solid III-solid II phase transition in PPNC1, the 2 H relaxation times of the -ND 3 group increase by approximately two orders of magnitude. For the solid II phase, the "0 = 90°" and the 0 = 0° orientations of the powder pattern do not relax with the same rate, indicating that the reorientation mechanism still involves jumps instead of smallangle diffusion [32].…”

Section: Ii) Reorientational Dynamics Of the -Nd 3 Group Obtained Fromentioning

confidence: 97%

Molecular Motion in Phenpropylammonium Chloride Studied by Deuterium NMR

Gruwel

Wasylishen

1992

Zeitschrift Für Naturforschung A

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Cation dynamics in phenpropylammonium chloride, C 6 H 5 (CH 2 ) 3 NH 3 Cr, were studied in three different solid phases by means of 2 H nmr. Both 2 H nmr line shapes and spin-lattice relaxation studies were performed on the ammonium head group, the adjacent methylene group and the phenyl-ring. In the low temperature phase, solid III, the -ND 3 group dynamics were dominated by C 3 jumps about the C-N axis. From the observed minima in T 1Z and T 1Q a quadrupole coupling constant of 165 ± 5 kHz was obtained. The 2 H nmr line shapes of the methylene group indicate that this group does not execute any large amplitude motion in the low temperature phase. In contrast, the phenyl ring deuterium nuclei give rise to line shapes characteristic of C 2 ring flips about the Cpara~C ipso aX * S "In the solid II phase the 2 H nmr line shapes of both the -ND ? and -CD 2 -groups are characterized by asymmetric Pake powder patterns. Since one of the principal components of the electric field gradient tensor remains temperature independent for both groups, it was concluded that these groups perform planar large-amplitude motions between two sites.Axially symmetric spectra were obtained for all three groups in the high temperature phase, solid I. The 2 H nmr line shapes indicate the presence of whole ion reorientation about a molecular axis. In addition, the -ND 3 groups perform C 3 jumps about the C-N axis and the -C 6 D 5 group display line shapes characteristic for rotational diffusion about the C para -C ipso axis.

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“…On the grounds that the rotational barrier for a methyl group is determined primarily by local chemical bonds rather than by the environment of the methyl group (Andrew et al, 1980;Ishima et al, 1991), the correlation time for the random jumps of the Met methyl groups of SSI at 20 "C was estimated from the low-temperature proton TI data of the crystalline amino acid qbmethionine (Andrew et al, 1976) by extrapolating it to 20 "C. A value even an order of magnitude smaller (10-l2 s) was estimated from deuterium TI data of crystalline L-methionine (Batchelder et al, 1983) by extrapolating the correlation times at low temperature to 20 "C. Whichever of the two values is adopted, this motion is faster than the Larmor precession (6.14 X lo7 Hz) by at least three orders of magnitude, and the TI and T2 values are not sensitive to the frequency of this motion. The consequence of this rapid motion is simply that the quadrupolar interaction is reduced by tion of the methyl axis (i.e., of the S,-C, bond), which may reflect the whole rotation of the protein molecule plus internal motions of the Met side chain.…”

Section: Protein In Solutionmentioning

confidence: 99%

“…Furthermore, because in methionine the rotation of the methyl group about its threefold axis is expected to be much more rapid (IO" Hz or more at 20°C) (Andrew et al. 1976;Batchelder et al, 1983) than the deuterium Larmor frequency and is unlikely to affect the spin-lattice relaxation time ( T I ) of the methyl deuterons, the mobility of its side chain (which affects the orientation of the methyl group) would be the main influence on T I . If slower internal motions (in the milli-to microsecond range) are present, they may be reflected in the line shape of the deuterium NMR spectrum for the solid-state protein, in which the overall rotation of the molecule is quenched.…”

mentioning

confidence: 99%

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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Methyl reorientation in polycrystalline amino acids and peptides: a deuteron NMR spin-lattice relaxation study

Cited by 140 publications

References 2 publications

Alamethicin Supramolecular Organization in Lipid Membranes from 19F Solid-State NMR

Alamethicin Supramolecular Organization in Lipid Membranes from 19F Solid-State NMR

Molecular Motion in Phenpropylammonium Chloride Studied by Deuterium NMR

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

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