Proton and carbon-13 nmr spectra of unsonicated lipid bilayers and biological membranes are generally dominated by strong proton–proton and proton–carbon dipolar interactions. As a result the spectra contain a large number of overlapping resonances and are rather difficult to analyse. Nevertheless, important information on the structure and dynamic behaviour of lipid systems has been provided by these techniques (Wennerstrom & Lindblom, 1977).

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Deuterium magnetic resonance: theory and application to lipid membranes.

Publisher Summary This chapter discusses solid state nuclear magnetic resonance of lipid bilayers. The shortcomings of conventional high-resolution spectroscopy when applied to lipid bilayers are presented. The resolution in multiple-pulse experiments has been limited to 1–2 ppm and these techniques have been useful only for studies of small molecules. A method for obtaining high-resolution spectra of solids relies on the spatial factor to attenuate and is referred to as dilute spin spectroscopy. It is found that since the oscillating components are adjusted to the same frequency, the spin systems are in resonance and mutual spin flips can occur and heat can flow between the reservoirs, and they equilibrate to a common spin temperature. It is convenient to add an echo pulse to the experiment at the dilute spin frequency, as is shown in the chapter. The purpose of this pulse is to delay data acquisition until the receiver and filters of the spectrometer recover from the radiofrequency pulse. It is suggested that the sidebands can be used to obtain information on chemical shift and electric field gradient tensors.

[8] Solid state nuclear magnetic resonance of lipid bilayers

Correlations between parameters characterizing the proton chemical shift tensors for O–H⋅⋅⋅O bonded protons in solids and O⋅⋅⋅O hydrogen bond distances and deuterium quadrupole coupling constants (e2qQ/h) are presented. The isotropic value of the chemical shift correlates very well with both RO⋅⋅⋅O and e2qQ/h, whereas the correlations involving the chemical shift anisotropy show much more scatter. A quantitative agreement is found with theoretical calculations performed by Ditchfield.

Correlations between proton chemical shift tensors, deuterium quadrupole couplings, and bond distances for hydrogen bonds in solids

Deuterium Magnetic Resonance: Applications in Chemistry, Physics and Biology

In macromolecules, the presence of H bonds is indicated by the spatial proximity and relative arrangement of the atoms involved, after the structure has been solved by either crystallography or NMR. A variety of NMR spectroscopic parameters has also been used for characterizing these pivotal interactions. These include the effect of such bonds on isotropic chemical shifts 2 and chemical shift anisotropy, 3 on the quadrupole coupling of 2H involved in a H bond, 4 on protection of exchange of the labile hydrogen with solvent, 5 and1H/2H fractionation. 6 In a recent remarkable report, Dingley and Grzesiek 7 were the first to demonstrate the presence of surprisingly largeJ couplings (6-7 Hz) between the H bond donating and accepting 15N nuclei in a Watson -Crick base pair in double-stranded RNA. This finding was confirmed by Pervushin et al., 8 and these authors additionally discovered the presence of a smaller (2 -4 Hz) J couplings between the imino hydrogen itself and the H bond accepting 15N nucleus. These couplings confirm the interaction between the electronic orbitals of the atoms involved, and most importantly they identify unambiguously the pairs of atoms involved in a given H bond. Although in organic chemistry the possibility of J couplings between atoms separated by less than the sum of the van der Waals radii has long been known, in particular for cases involving 19F,9 Summers et al. were the first to detect such couplings in a protein.10 They observed these interactions, ranging from 0.3 to 4 Hz, between the metal (Cd and Hg) in rubredoxin and backbone amide protons H-bonded to the S atoms ligating the metal. Remarkably, they also found J coupling between an alanyl methyl group, adjacent to such an S atom, and the metals. Here, we demonstrate for the protein ubiquitin that small J couplings can be observed across H bonds between the donating 15N atom and the accepting carbonyl/carboxyl 13C. The scheme used for detecting this through-H-bond J connectivity (JNC′) is essentially the regular CT-HNCO experiment, 11 optimized for the detection of these small 15N-13C′ couplings (Figure 1). The magnitude ofJNC′ is then determined through the principle of quantitative analysis of cross-peak intensity. 12 In brief, the scheme of Figure 1 is executed three times: (A) with the dephasing time, 2T, tuned to 1/(2JNC′), (B) with 2T ) 3/(2JNC′), (C) with 2T ) 4/(2JNC′). Values ofJNC′ in polypeptides are quite homogeneous (15 ( 1 Hz),13 and much larger than the JNC′ which are the focus of this study. The signal intensity observed for a correlation between N and C ′ with couplingJNC′ is proportionate to exp( 4T/T2) sin(2πJNC′T) Πk cos(2πJNkT), where the product extends over all other carbonyl/carboxyl carbons coupled to the 15N of interest with coupling constants JNk, andT2 is the15N transverse relaxation time. The dephasing times, 2 T, used in this study have a maximum duration of 133.2 ms, and cos (2πJNkT) ≈ 1 for JNk e 1 Hz. Hence, a good approximation for T2 is obtained from the ratio between experiments A and B. To a good approximation, therefore, the magnitude of the small J coupling between N and k can be derived from

Identification of the Hydrogen Bonding Network in a Protein by Scalar Couplings

A deuteron magnetic resonance study is made of single crystals of CuSO4·5D2O between 130° and 360°K. The electric quadrupole coupling constant, the asymmetry parameter, and the directions of the principal axes of the field‐gradient tensor are determined for each deuteron at 133.2° and 294.8°K. At low temperatures ten pairs of lines are observed, corresponding to five nonequivalent stationary water molecules. At temperatures above room temperature, five pairs of lines are observed; these are shown to result from fast molecular reorientation about the bisecting axis of each water molecule. An activation energy for the 180° reorientational motion is derived for each water molecule and is discussed in relation to the lonepair coordination of the oxygen atom of the water molecule and the hydrogen‐bond strength. The field‐gradient tensor for each stationary water molecule is discussed in relation to the structure of the hydrogen‐bond system. For relatively weak asymmetric hydrogen bonds of O–H···O, an empirical...

Deuteron Magnetic Resonance Study of Cupric Sulfate Pentahydrate

Deuteron magnetic resonance (DMR) of single crystals of Cu(DCOO) 2 ·4D 2 O has been studied from 153°K to 291°K to reveal the changes in the structure and the motions of the crystalline water molecules due to the paraelectric-antiferroelectric phase transition ( T c =246.1±0.2°K). Above T c , all the DMR lines of water molecules are broadened out by fast motions of deuterons among seven sites. Below T c , 20 pairs of DMR lines are observed corresponding to four water molecules in stable position and two formate ions and their a c -plane enantiomorphs. Following conclusions are derived from measurements of temperature and angular dependences of the quadrupole splittings for these DMR lines. The phase transition is an order-disordering type of water molecules. In the antiferroelectric phase, the unit cell doubling occurs along the c -axis direction and the space group is P 2 1 / n . The structure involves a three dimensional ordering of water molecules. The structure of hydrogen-bond network is determined. ...

Deuteron Magnetic Resonance Study of Cupric Formate Tetrahydrate Cu(DCOO)2·4D2O

A study on the Zeeman effect of Cl 35 nuclear quadrupole resonance spectrum was carried out on a single crystal of cyanuryl chloride. Three distinct q -tensors were found in this crystal, two of them being equivalent. The directions of the principal axes were determined within the accuracy of 1° . It was concluded that in the crystal all molecules are disposed parallel (or antiparallel) to one another and three C–Cl bonds of a molecule are on a plane, making an angle 120° with one another, one of them being not equivalent to the other two. A large asymmetry parameter, 0.26, was obtained. From the coupling constant and the asymmetry parameter, the double bond character and the ionic character of C–Cl bonds were estimated to be 10% and 17%, respectively. The large double bond character was considered to be associated with the large electronegativity of nitrogen atoms in the ring.

Zeeman Effect of Nuclear Quadrupole Resonance Spectrum in Cyanuryl Chloride

The pure quadrupole resonance spectra were observed on Cl 35 and Cl 37 in BCl 3 and Br 79 and B 81 in BBr 3 at several temperatures. The spectrum of each nucleus consists of characteristic doublet (ν I and ν II ) with the intensity ratio of ca. 3 to 5. The Zeeman study with a single crystal of BBr 3 was also carried out at liquid nitrogen temperature (77°K), to determine the asymmetry parameter η. The results are as follows:

Nuclear Quadrupole Spectra of Boron Trichloride and Tribromide

Deuteron and 23 Na magnetic resonances are measured of single crystals of NaD 3 (SeO 3 ) 2 between 134°K and 298°K to reveal the nature of the ferroelectric transition ( T c ∼267°K). Deuteron resonance lines D a and D b (relative intensity 1:2) above T c split into two and into four, respectively. The 23 Na resonance line above T c also splits into two below T c . Following conclusions are derived from measurements of temperature and angular dependences of the quadrupole splittings for these deuteron and 23 Na resonance lines. All the hydrogen atoms are linked with moderately strong hydrogen bonds, and are jumping back and forth in the double well potential above T c . The phase transition is accompanied not only by order-disordering of hydrogen atoms in hydrogen bonds, but also by slight rotations of SeO 3 - ions and by a slight distortion of lattice in the neighborhood of Na + ions. The crystalline symmetry below T c is monoclinic, and the cell-doubling occurs along the b axis. Hydrogen-bond network bel...

Takehiko Chiba

Papers

Deuteron Magnetic Resonance Study of Cupric Sulfate Pentahydrate

Deuteron Magnetic Resonance Study of Cupric Formate Tetrahydrate Cu(DCOO)2·4D2O

Zeeman Effect of Nuclear Quadrupole Resonance Spectrum in Cyanuryl Chloride

Nuclear Quadrupole Spectra of Boron Trichloride and Tribromide

Hydrogen-Bond Network and Ferroelectric Transition in Sodium Trihydrogen Selenite, NaD 3 (SeO 3 ) 2 by Nuclear Magnetic Resonance Study