Phospholipids Bicelles Assembly Simulation Program

FIGURE 10.2 Normalized solid-state 2H NMR spectra of a Tm3+-doped bicelle sample showing the various temperature-dependent phases of the Tm3+-doped bicelle system. 2H NMR spectra were taken at various static temperatures in a resonant frequency of 46.07 MHz. The temperature at which each spectrum was taken is noted on the left of the spectrum. of hysteresis effects.82 Firestone and coworkers showed that their liquid-crystalline system magnetically aligned at a low temperature, corresponding to...

Distance Measurements For Torsion Angle Determination

In general, the distance (d) between two atoms separated by three covalent bonds depends on the torsion angle 0 around the central bond sinusoidally as d2 Ci2 + c2 + c2 - 2c1c2 cos a1 -2c2c3 cos a2 + 2c1c3 cos a1 cos a2 - 2c1c3 sin a1 sin a2 cos 8 where a1 and a2 are bond angles and c1, c2, and c3 are bond lengths. Thus, the distance between two nuclei separated by three bonds gives information on the dihedral angle of the central bond. Both homonuclear and heteronuclear distance experiments...

Nmr In Lipid Bilayers

Glass-supported oriented phospholipid bilayers containing membrane proteins accomplish the principal requirements of immobilizing and orienting the protein for solid-state NMR structure determination. The planar lipid bilayers are supported on glass slides and are oriented in the NMR probe so that the bilayer normal is parallel to the field of the magnet, as shown in Figure 8.5a. The choice of lipid can be used to control the lateral spacing between neighboring phospholipid molecules, as well...

References

Haeberlen, U., High-Resolution NMR in Solids. Selective Averaging, Academic Press, New York, 1976. 2. Mehring, M., Principles of High Resolution NMR in Solids, Springer, New York, 1983. 3. Gerstein, B.C. and Dybowski, C.R., Transient Techniques in NMR of Solids. An Introduction to Theory and Practice, Academic Press, Orlando, FL, 1985. 4. Schmidt-Rohr, K. and Spiess, H.W., Multidimensional Solid-State NMR and Polymers, Academic Press, London, 1996. 5. McDowell, L.M. and Schaefer, J.,...

Homonuclear Recoupling Experiments

For spin-pair measurements, homonuclear experiments have primarily been applied to 13C, and less often to 31P and 19F. Homonuclear couplings between 15N spins in peptides and proteins are generally too weak to be structurally informative, although some exceptions have been demonstrated.57 Although possible in special circum-stances,58 it is in general difficult to prepare protein samples with unique 1H-1H spin pairs therefore, 1H-1H measurements require techniques for addressing clusters of...

Info

FIGURE 3.1 (a) Amino acid sequence and secondary structure of E. coli thioredoxin generated by PDBsum37 using the PDB file 2trx.ent.50 The C-terminal fragment encompassing amino acid residues 74-108 is highlighted in gray. (b) Tertiary structure generated using Molscript51 and rendered using Raster3D.52,53 The N-terminal fragment (residues 1-73) is shown in dark grey the C-terminus (residues 74-108) is in light gray. Arg-73 at the cleavage site is depicted using the stick representation. The...

Solidstate Nmr Techniques For Alkali Metal Ions

All NMR-active alkali metal isotopes have an atomic nucleus, the nuclear spin quantum number of which is greater than 1 2 (S > 1 2). These nuclei are known as quadrupolar nuclei. In this chapter, we focus on 23Na (natural abundance 100 ) and 39K (natural abundance 93 ), which are both S 3 2 nuclei. The quadrupolar nature of these alkali metal nuclei makes it necessary to use solid-state NMR techniques that are quite different from those developed for more familiar spin-1 2 nuclei such as 13C...

Nmr In Micelles

Solution NMR methods rely on rapid molecular reorientation for line narrowing and can be successfully applied to membrane proteins in micelles.1423-35 The size limitation is substantially more severe than for globular proteins because the many lipid molecules associated with each polypeptide slow its overall reorientation rate. Micelles afford rapid and effectively isotropic reorientation of the protein, and their amphipathic nature simulates that of membranes, offering a realistic alternative...

Sample Design and Experiment Goals

Designing experiments and suitably labeled samples for spin-pair measurements requires sufficient background information (from mutagenesis, homology modeling, crystallography, previous NMR experiments, etc.) to construct specific structural hypotheses. Given the range of distance measurement techniques summarized above, some foresight about distances that are likely to be observed is the first prerequisite to successful application of spin-pair methods. The second requirement is the ability to...

Experimental Protocols For Resonance Assignments

Experimentos Resonancia

Several successful de novo resonance assignment protocols have been presented in the recent literature.13 16 19-20-22 On the basis of these studies, salient experimental considerations can be outlined for high-resolution MAS studies of uniformly enriched polypeptides. As will be discussed below, using thioredoxin as an example, two-dimensional spectroscopy at high magnetic fields 17.6 T yields nearly complete resonance assignments. For moderate-size proteins, backbone assignments for a fraction...