Deuterium off-resonance rotating frame spin-lattice relaxation of macromolecular bound ligands (original) (raw)
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Biopolymers, 1990
The ' 'C off-resonance rotating frame spin-lattice relaxation technique is applicable to the study of protein rotational diffusion behavior in a variety of experimental situations. The original formalism of James and co-workers (1978) ( J . Amer. Chem. SOC. 100, [3590][3591][3592][3593][3594] was constrained by the assumption of random isotropic reorientational motion. Here we include in the formalism anisotropic tumbling, and present the results of computer simulations illustrating the differences between anisotropic and isotropic reorientational motion for the off-resonance rotating frame spin-lattice relaxation experiment. In addition, we have included chemical shift anisotropy of the peptide carbonyl carbon as an additional relaxation mechanism contribution, to permit high-field nmr protein rotational diffusion measurements. 1990 .lohri b'iley & Sons, Inc.
Journal of Magnetic Resonance, 1998
N off-resonance rotating frame relaxation can be applied to tematic deviations of R 2 , and the relaxation contribution due the study of internal dynamics in proteins in the millisecond to to chemical exchange can be estimated from its proportionalmicrosecond regime. We show that the performance of existing ity to the square of the static field strength (2). A disadvanmethods can be improved by application of simultaneous amplitage of this method is obviously the collection of data from tude and phase-modulated adiabatic RF pulses to align the nuclear different NMR spectrometers, which may not be accessible.
Journal of the American Chemical Society, 1976
I H and "C relaxation data relating to the methionine methyl group i n the peptide tetragastrin are reported. An analysis of methyl spin-lattice relaxation times and the heteronuclear Overhauser effect is presented. This analjsis illustrates an approach to the determination of motional information when dipolar and spin-rotation interactions dominate the relaxation mechanism and when the effect of cross correlations must be considered. The importance of these effects in studies of peptides in solution by N M R relaxation is emphasized. (42) The question oi the effects of cross correlations when the dipolar and spin-rotation are both operative will be discussed in a forthcoming publication. See Note Added in Proof.
Journal of the American Chemical Society, 2002
New pulse sequences are presented for the measurement of the relaxation of deuterium double quantum, quadrupolar order, and transverse antiphase magnetization in 13 CH2D methyl groups of 15 N-, 13 C-labeled, fractionally deuterated proteins. Together with previously developed experiments for measuring deuterium longitudinal and transverse decay rates [Muhandiram, D. R.; Yamazaki, T.; Sykes, B. D.; Kay, L. E. J. Am. Chem. Soc. 1995, 117, 11536], these schemes allow measurement of the five unique decay constants of a single deuteron, providing an unprecedented opportunity to investigate side-chain dynamics in proteins. All five deuterium relaxation rates have been measured for deuterons in the methyl groups of the B1 immunoglobulin binding domain of peptostreptococcal protein L and the N-terminal SH3 domain from the protein drk. Since values of the spectral density function at only three different frequencies contribute to the five relaxation rates, the self-consistency of the relaxation data is readily established. Very good agreement is obtained between calculated parameters describing the amplitudes and time scales of motion when different subsets of the relaxation data are employed.
Magnetic Resonance in Chemistry, 1998
13C NMR spinÈlattice relaxation and 13CÈM1HN nuclear Overhauser measurements were performed on the encapsulation complex between [2.2]paracyclophane and a dimeric capsule known as the hydroxy "softball.Ï The data were analyzed using the formalism for an isotropically di †using sphere. The binding constant for the complex is (3.5^0.5) ] 103 l mol~1 in at 295 K. The average dipoleÈdipole relaxation time is 0.45^0.04 s CDCl 3 for the CH vectors of the encapsulated [2.2]paracyclophane and 0.30^0.03 s for the skeleton of the hydroxy "softball.Ï The correlation time for the skeleton of the hydroxy "softballÏ is 2.7 ] 10~10 s. The corresponding correlation time for the encapsulated [2.2]paracyclophane is calculated to be 1.2 ] 10~10 s. This results in an average dynamic coupling constant, s, of 0.47, indicating shape complementarity and correlated motion between the hydroxy "softballÏ and the [2.2]paracyclophane. 1998 John Wiley & Son Ltd.
Rocking motion in solid proteins studied by the 15N proton-decoupled R1ρ relaxometry
Physical Chemistry Chemical Physics, 2023
Recently it has been revealed that proteins in solid samples undergo slow overall rocking. The parameters of this motion depend on intermolecular interactions. Therefore, the characterization of the rocking motion enables one to investigate protein-protein interactions. NMR R 1r relaxometry is the most suitable tool to study slow molecular motions. However, the time scale of the rocking motion is on the edge of the dynamics window of the standard R 1r experiment, precluding the R 1r data analysis from being precise and reliable. In this work, we apply a modified R 1r relaxation method to characterize the slow motion in solids with much higher precision and reliability. The modification is the simultaneous use of a strong 1 H-CW pulse and a weak/moderate 15 N spin-lock pulse. We demonstrate theoretically and experimentally that under this condition, R 1r decays have a significantly better signal-to-noise ratio and a much shorter ''dead time'' caused by the initial oscillations compared to the conventional R 1r experiment. Moreover, the proton-decoupled R 1r 's can be measured at a much smaller difference between the spin-lock and MAS frequencies; thus, much slower molecular motions can be sampled. The proton decoupling during the 15 N spin-lock pulse also suppresses the interfering coherent spin-spin relaxation pathway at low spin-lock fields, which overlaps the Bloch-McConnell (chemical exchange) range of R 1r dispersions. The protondecoupled and standard R 1r experiments were used to study the rocking motion of 15 N, 2 H-enriched protein GB1 in two solid forms, microcrystals and lyophilized amorphous powder. The most striking finding is that the correlation function of this motion consists of two components with very different correlation times, 2-20 ms and a few hundred ms. The rocking motion parameters in microcrystals and powder are quite different, revealing the distinct nature of inter-protein interactions in these two samples.
Water molecule contributions to proton spin–lattice relaxation in rotationally immobilized proteins
Journal of Magnetic Resonance, 2009
Spin-lattice relaxation rates of protein and water protons in dry and hydrated immobilized bovine serum albumin were measured in the range of 1 H 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 1 H 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 1 H spin relaxation.
Chemical Physics Letters, 2007
In this Letter we propose a development of a NMR methodology to study ligand-macromolecular receptor interactions, based on the analysis of proton selective spin-lattice relaxation rate enhancements of the ligand, to calculate an affinity index, related to strength of the interaction process. In this work we modified this index by normalization to the relaxation rate of the free ligand, in order to take into account the effects of motional anisotropies and different proton densities. This approach also allowed the calculation of the relaxation rate of the bound ligand as well as the equilibrium constant of the interaction process.
Analysis of laboratory-frame and rotating-frame cross-relaxation buildup rates from macromolecules
Journal of Magnetic Resonance (1969), 1989
A quadratic approximation of cross-relaxation buildup rates is described for identifying and correcting for indirect magnetization transfer effects in macromolecular spectra. This approach has permitted the accurate determination of interproton distances in a protein of molecular weight 6000, turkey ovomucoid third domain. An illustration is given of the analysis of a three-spin system to yield a distance between two protons that lacked resolved direct NOESY and ROESY cross peaks. o 1989 Academic press, IIIC.