Nuclear magnetic relaxation dispersion study of the dynamics in solid homopolypeptides

Goddard, Yanina A.; Korb, Jean-Pierre; Bryant, Robert G.

doi:10.1002/bip.20714

Cited by 6 publications

(12 citation statements)

References 38 publications

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“…The difference is in the high field portion of the relaxation dispersion profile, which at low temperatures, preserving the power law, is displaced to higher relaxation rates relative to the extrapolation of the low field profile. This phenomenon was previously described in [21; 22], where it is shown that the increase in the relaxation rates is due to fast motion of covalently bound protein side-chain groups. Motion of phenyl rings was observed at low frequencies and elevated temperatures for polyphenylalanine while motions of methyl groups dominate at high frequency and low temperatures [22].…”

Section: Resultssupporting

confidence: 53%

“…This phenomenon was previously described in [21; 22], where it is shown that the increase in the relaxation rates is due to fast motion of covalently bound protein side-chain groups. Motion of phenyl rings was observed at low frequencies and elevated temperatures for polyphenylalanine while motions of methyl groups dominate at high frequency and low temperatures [22]. Even though the motion of side-chain methyl groups is present at all temperatures, it is sufficiently slow only below 180 K for dry BSA to enter the observation window and offset the relaxation rate constant to larger values at the highest frequencies as shown in Fig.…”

Section: Resultssupporting

confidence: 53%

“…As can be seen from Fig. 2, the magnetic relaxation dispersions at low temperature differ from that observed at 302 K [40]. The difference is in the high field portion of the relaxation dispersion profile, which at low temperatures, preserving the power law, is displaced to higher relaxation rates relative to the extrapolation of the low field profile.…”

Section: Resultsmentioning

confidence: 84%

“…As a consequence, motions that relax one group efficiently relax the whole 1 H spin population, which is observed as a single broad resonance line. Recent MRD studies of dry proteins and polypeptides over wide temperature ranges revealed the nature of the side-chain contributions to the 1 H spin relaxation [21; 22]. At high and low frequencies, the field dependence is a power law because the main-chain fluctuations also modulate the side-chain couplings.…”

Section: Introductionmentioning

confidence: 99%

“…A displacement of the high and low frequency power laws is caused by the side chain motions, which create a transition when the side-chain frequency approximates the proton Larmor frequency. The effects of the side-chain dynamics move into the experimental frequency range only at low temperatures using currently convenient magnetic fields [21; 22]. The present experiments focus on relaxation contributions of protein-bound water dynamics, which in some cases look like a side-chain contribution in that the water motions may be coupled to the backbone dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Water molecule contributions to proton spin–lattice relaxation in rotationally immobilized proteins

Goddard

Korb

Bryant

2009

Journal of Magnetic Resonance

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Spin-lattice relaxation rates of protein and water protons in dry and hydrated immobilized bovine serum albumin were measured in the range of 1H Larmor frequency from 10 kHz to 30 MHz at temperatures from 154 to 302 K. The water proton spin-lattice relaxation reports on that of protein protons, which causes the characteristic power law dependence on the magnetic field strength. Isotope substitution of deuterium for hydrogen in water and studies at different temperatures expose three classes of water molecule dynamics that contribute to the spin-lattice relaxation dispersion profile. At 185 K, a water 1H relaxation contribution derives from reorientation of protein-bound molecules that are dynamically uncoupled from the protein backbone and is characterized by a Lorentzian function. Bound water molecule motions that can be dynamically uncoupled or coupled to the protein fluctuations make dominant contributions at higher temperatures as well. Surface water translational diffusion that is magnetically two-dimensional makes relaxation contributions at frequencies above 10 MHz. It is shown using isotope substitution that the exponent of the power law of the water signal in hydrated immobilized protein systems is the same as that for protons in lyophilized proteins over four orders of magnitude in the Larmor frequency, which implies that changes in the protein structure associated with hydration do not affect the 1H spin relaxation.

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Section: Resultssupporting

confidence: 53%

Section: Resultssupporting

confidence: 53%

Section: Resultsmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Water molecule contributions to proton spin–lattice relaxation in rotationally immobilized proteins

Goddard

Korb

Bryant

2009

Journal of Magnetic Resonance

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Recent development in 1H NMR relaxometry

Kruk

Florek–Wojciechowska

2020

Annual Reports on NMR Spectroscopy

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Water and Backbone Dynamics in a Hydrated Protein

Diakova

Goddard

Korb

et al. 2010

Biophysical Journal

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Rotational immobilization of proteins permits characterization of the internal peptide and water molecule dynamics by magnetic relaxation dispersion spectroscopy. Using different experimental approaches, we have extended measurements of the magnetic field dependence of the proton-spin-lattice-relaxation rate by one decade from 0.01 to 300 MHz for (1)H and showed that the underlying dynamics driving the protein (1)H spin-lattice relaxation is preserved over 4.5 decades in frequency. This extension is critical to understanding the role of (1)H(2)O in the total proton-spin-relaxation process. The fact that the protein-proton-relaxation-dispersion profile is a power law in frequency with constant coefficient and exponent over nearly 5 decades indicates that the characteristics of the native protein structural fluctuations that cause proton nuclear spin-lattice relaxation are remarkably constant over this wide frequency and length-scale interval. Comparison of protein-proton-spin-lattice-relaxation rate constants in protein gels equilibrated with (2)H(2)O rather than (1)H(2)O shows that water protons make an important contribution to the total spin-lattice relaxation in the middle of this frequency range for hydrated proteins because of water molecule dynamics in the time range of tens of ns. This water contribution is with the motion of relatively rare, long-lived, and perhaps buried water molecules constrained by the confinement. The presence of water molecule reorientational dynamics in the tens of ns range that are sufficient to affect the spin-lattice relaxation driven by (1)H dipole-dipole fluctuations should make the local dielectric properties in the protein frequency dependent in a regime relevant to catalytically important kinetic barriers to conformational rearrangements.

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Nuclear magnetic relaxation dispersion study of the dynamics in solid homopolypeptides

Cited by 6 publications

References 38 publications

Water molecule contributions to proton spin–lattice relaxation in rotationally immobilized proteins

Water molecule contributions to proton spin–lattice relaxation in rotationally immobilized proteins

Recent development in 1H NMR relaxometry

Water and Backbone Dynamics in a Hydrated Protein

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