NMR order parameter analysis of a peptide plane aligned in a lyotropic liquid crystal

Abstract

A full order parameter analysis has been carried out on a peptide plane of gramicidin A in aligned phospholipid bilayers. The most ordered molecular axis was determined to be the helical long axis of the molecule, possessing an order parameter of 0.93 -4-0.03 parallel to the bilayer normal, and an axial symmetry of -0.06 d: 0-04.

Comparative analysis of the orientation of transmembrane peptides using solid-state 2H- and 15N-NMR: mobility matters

“…In several recent approaches, peptide dynamics has been duly considered in 2 H-NMR analyses, e.g., by implementing time-averaged Gaussian distributions of the orientation angles (Strandberg et al 2009b), by obtaining distributions of peptide orientation angles with the help of MD simulations (Kim et al 2011;Monticelli et al 2010) or free energy calculations , or by simultaneously fitting 2 H-, 13 C-, and 15 N-NMR data (Holt et al 2010;Separovic et al 1993). Likewise, the influence of dynamics on PISEMA spectra and 2 H quadrupolar splittings (Kim et al 2011) has been considered using ensemble-restrained MD simulations.…”

The development of solid-state NMR of membrane proteins

“…Contemporarily, Cornell and coworkers [23, 102] showed that 13 C′ labeled gramicidin undergoes the same type of motional averaging in phospholipid bilayers. The results with 13 C labels in gramicidin [98] were confirmed with 2 H [49, 104] and 15 N labeled gramicidin; Cross and coworkers [30] showed that the 15 N powder pattern in an unoriented bilayer sample was axially symmetric, as required by motional averaging about the bilayer normal. In a highly definitive experiment, Cross and coworkers utilized gramicidin labeled at a single site to show with a two-dimensional SLF experiment that the motionally averaged chemical shift and dipolar coupling principal elements were collinear, while in a static sample they differ in alignment by about 17°.…”

Construction of 1

“…Fig. 6 shows the one-and two-dimensional solid-state NMR spectra of uniformly 15 N-labeled hAPP-TM peptide in 14-O-PC/ 6-O-PC (q = 3.2) bicelles aligned magnetically with their normals perpendicular to the magnetic field obtained with the home-built probe. The 15 N chemical shifts, which depend on the orientation of the transmembrane helix (70 -100 ppm), are obtained from the 1D spectrum, as shown in Fig.…”

“…[6][7][8] Magnetically aligned bicelle samples in an NMR tube [9][10][11][12][13] or planar lipid bilayer samples which are mechanically aligned and supported on glass slides are often used for these experiments. [14][15][16][17][18] Especially, the sample preparation of bicelles is easier and bicelle samples are more stable than mechanically oriented lipid bilayer samples between glass plates and they can even be kept for more than a year. Therefore, in recent years, magnetically aligned bicelle samples have frequently been used to determine the structure of membrane proteins by solid-state NMR spectroscopy.…”

“…The orientational restraints resulting from membrane proteins in a lipid environment can be examined by 1 H- 15 N heteronuclear dipolar coupling solid-state NMR experiments, such as polarization inversion spin exchange at the magic angle (PISEMA) [2][3][4][5][6] or high resolution separated local field spectroscopy based on magic-sandwich pulses (SAMMY). [6][7][8] Magnetically aligned bicelle samples in an NMR tube [9][10][11][12][13] or planar lipid bilayer samples which are mechanically aligned and supported on glass slides are often used for these experiments.…”