Hydration-optimized oriented phospholipid bilayer samples for solid-state NMR structural studies of membrane proteins

Marassi, Francesca M.; Crowell, Kevin J.

doi:10.1016/s1090-7807(02)00182-9

Cited by 32 publications

(36 citation statements)

References 28 publications

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“…heating in lipid systems is the water content. 45 In this work, the number of water molecules per lipid was ¾13 but considerably higher hydration levels are not uncommon. Owing to elevated losses of r.f.…”

Section: Discussionmentioning

confidence: 76%

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Heating caused by radiofrequency irradiation and sample rotation in ¹³C magic angle spinning NMR studies of lipid membranes

Dvinskikh

Castro

Sandström

2004

Magnetic Reson in Chemistry

103

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Application of rapid sample rotation and radiofrequency irradiation in magic angle spinning (MAS) NMR of lipid bilayers can significantly increase the sample temperature. In this work, we studied the extent of heating during the acquisition of 1H-decoupled 13C MAS spectra of hydrated dimyristoylphosphatidylcholine (DMPC) in the L(alpha) phase. First, we describe a simple procedure for determining the increase in temperature by observing the shift of the 1H water signal. The method is then used to identify and assess the various factors that contribute to the sample heating. The important factors discussed in this paper include: (i) the spinning speed, (ii) the variable-temperature gas pressure, (iii) the rotor geometry, (iv) the power, duration and frequency of the radiofrequency irradiation and (v) the hydration level. A comparison of different heteronuclear decoupling schemes in terms of their ability to produce highly resolved 13C spectra of DMPC is also reported.

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Section: Discussionmentioning

confidence: 76%

“…Sample heating can be compensated for by adjusting the temperature of the VT gas, and significantly reduced by (i) choosing efficient decoupling schemes, (ii) using small rotor diameters and (iii) optimizing the hydration level. 45 It is hoped that the results reported here will assist in future 13 C MAS NMR studies of lipid bilayer samples.…”

Section: Discussionmentioning

confidence: 78%

Heating caused by radiofrequency irradiation and sample rotation in ¹³C magic angle spinning NMR studies of lipid membranes

Dvinskikh

Castro

Sandström

2004

Magnetic Reson in Chemistry

103

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“…Samples of TM peptides were prepared either by detergent mediated reconstitution 9,32 or organic solvent reconstitution. 33,34 Full-length protein samples were prepared exclusively via detergent mediated reconstitution.…”

Section: Oriented Bilayer Samplesmentioning

confidence: 99%

“…PISEMA spectra were simulated for an 18-residue˛-helix with 0°rotation about the helical axis ( D 0°) while the helix axis tilt angle ( ) and backbone torsion angles ( , ) were allowed to vary, as indicated. Randomized variations in ( , ) about the idealized values ( D 60°, D 45°) 38 for each residue were generated using a random number generator within The relative orientation (Â) between the chemical shift tensor element 33 and jj of the dipolar tensor was set to 17°, consistent with previous simulations 30 and experiments. 39 All 15 N-chemical shifts were referenced as described above for NMR data acquisition.…”

Section: Pisema Spectra Simulationsmentioning

confidence: 99%

Lipid bilayers: an essential environment for the understanding of membrane proteins

Page

et al. 2007

Magn. Reson. Chem.

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Membrane protein structure and function is critically dependent on the surrounding environment. Consequently, utilizing a membrane mimetic that adequately models the native membrane environment is essential. A range of membrane mimetics are available but none generates a better model of native aqueous, interfacial, and hydrocarbon core environments than synthetic lipid bilayers. Transmembrane α-helices are very stable in lipid bilayers because of the low water content and low dielectric environment within the bilayer hydrocarbon core that strengthens intrahelical hydrogen bonds and hinders structural rearrangements within the transmembrane helices. Recent evidence from solid-state NMR spectroscopy illustrates that transmembrane α-helices, both in peptides and full-length proteins, appear to be highly uniform based on the observation of resonance patterns in PISEMA spectra. Here, we quantitate for the first time through simulations what we mean by highly uniform structures. Indeed, helices in transmembrane peptides appear to have backbone torsion angles that are uniform within ± 4°. While individual helices can be structurally stable due to intrahelical hydrogen bonds, interhelical interactions within helical bundles can be weak and nonspecific, resulting in multiple packing arrangements. Some helical bundles have the capacity through their amino acid composition for hydrogen bonding and electrostatic interactions to stabilize the interhelical conformations and solid-state NMR data is shown here for both of these situations. Solid-state NMR spectroscopy is unique among the techniques capable of determining three-dimensional structures of proteins in that it provides the ability to characterize structurally the membrane proteins at very high resolution in liquid crystalline lipid bilayers.

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“…This method has a history back in the early 70's when the first pfg-NMR diffusion measurements were performed [2,14]. In general there is no "best" method of obtaining a good oriented sample and experience combined with a flexible thinking has produced many different approaches to this problem [9,11,15,18,19].…”

Section: Preparation Of Macroscopically Aligned Lipid Bilayersmentioning

confidence: 99%

Pfg NMR studies of lateral diffusion in oriented lipid bilayers

Orädd

Lindblom

2005

Journal of Spectroscopy

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Abstract. The pfg-NMR diffusion technique is proposed to have an appreciable potential for future biophysical investigations in the field of membrane biology. Topics like transport of molecules both across and in the plane of the membrane can be successfully studied, as well as the formation of lipid domains and their intrinsic dynamics can be scrutinized. This short review will introduce the fundamental aspects of orientation dependent NMR interactions and the technique of macroscopically oriented bilayers for eliminating the unwanted effects of those interactions. The pfg-NMR technique will be briefly introduced and finally, some recent results illustrating the potential of the method are presented. Orientation dependent NMR interactionsThe NMR spectrum for a general spin system is determined by the spin Hamiltonian, H, which consists of a number of interaction terms, of which the following four terms are of interest:where H Z is the Zeeman term and the next three terms represent the static interactions. The static interactions have a common scaling term, (1/2)(3 cos 2 θ − 1), which is the second Legendre polynomial, P 2 (θ), where θ is an angle that relates the principle coordinate system of the specific interaction to the main magnetic field (B 0 ) [12]. This will have the following effects on the observed NMR spectrum:-H CSA -The chemical shift anisotropy that represents the effect of induced magnetic fields due to orbital electronic motions, i.e. the chemical shift. Will change the chemical shift of the spectrum with a factor proportional to P 2 (θ). -H Q -The quadrupole interaction between the nuclear quadrupole moment and the surrounding electric field gradient. Will scale the quadrupolar coupling constant observed for nuclei with spin > 1/2 according to P 2 (θ). -H D -The dipolar interaction that represents the magnetic interaction between dipoles. Due to simultaneous coupling to several different dipoles this term will give rise to a linebroadening, which is proportional to P 2 (θ).For cos θ = 1/ √ 3, i.e. θ = 54.7 • , the scaling term (1/2)(3 cos 2 θ − 1) becomes zero and the static interactions "magically" disappear. This condition is generally hard to obtain since θ is distributed randomly in a non-oriented sample so one has to use special techniques in order to remove the static interactions. In the commonly used solid-state NMR technique, where magic angle spinning (MAS) is utilized, the sample is transferred into a rotor that can be spun at very high spinning rates. spinning of the sample causes all the static interactions to be projected onto the spinning axis of the rotor, which is then turned to the magic angle (54.7 • ) with respect to B 0 , thereby removing all the static interactions in the sample [16]. For liquid crystalline bilayers, on the other hand, the fast lateral reorientation and intermolecular rotation about the long axis of the molecules takes the role of the rotor and partially averages the interactions to leave only the part that is parallel to the normal with the bilayer. Thus...

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Hydration-optimized oriented phospholipid bilayer samples for solid-state NMR structural studies of membrane proteins

Cited by 32 publications

References 28 publications

Heating caused by radiofrequency irradiation and sample rotation in ¹³C magic angle spinning NMR studies of lipid membranes

Heating caused by radiofrequency irradiation and sample rotation in ¹³C magic angle spinning NMR studies of lipid membranes

Lipid bilayers: an essential environment for the understanding of membrane proteins

Pfg NMR studies of lateral diffusion in oriented lipid bilayers

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Hydration-optimized oriented phospholipid bilayer samples for solid-state NMR structural studies of membrane proteins

Cited by 32 publications

References 28 publications

Heating caused by radiofrequency irradiation and sample rotation in 13C magic angle spinning NMR studies of lipid membranes

Heating caused by radiofrequency irradiation and sample rotation in 13C magic angle spinning NMR studies of lipid membranes

Lipid bilayers: an essential environment for the understanding of membrane proteins

Pfg NMR studies of lateral diffusion in oriented lipid bilayers

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Product

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Heating caused by radiofrequency irradiation and sample rotation in ¹³C magic angle spinning NMR studies of lipid membranes

Heating caused by radiofrequency irradiation and sample rotation in ¹³C magic angle spinning NMR studies of lipid membranes