@article {2264,
	title = {The hand of the filamentous bacteriophage helix},
	journal = {European Biophysics Journal with Biophysics Letters},
	volume = {37},
	number = {6},
	year = {2008},
	note = {ISI Document Delivery No.: 314QDTimes Cited: 1Cited Reference Count: 30Straus, S. K. Scott, W. R. P. Marvin, D. A.},
	month = {Jul},
	pages = {1077-1082},
	type = {Article},
	abstract = {Filamentous bacteriophage (Inovirus) is a widely studied model system in molecular biophysics. The structure of the virion has been analysed by various methods, but the methods have seldom questioned the hand of the virion helix. The hand of the helix relating the protein subunits in the class II virus strain Pf1 was chosen by calculating an electron-density distribution from X-ray fibre diffraction data, using a maximum-entropy method, but to our knowledge this method has not been used for a similar purpose in any other system. Moreover, this same hand was extended only by analogy, with no direct analysis of the corresponding data, to the class I virus strain Ff (fd, f1, M13), which has a different helix symmetry. Here we use published solid-state NMR data to confirm the validity of the hand of Pf1 chosen by the maximum-entropy method, and to confirm the extension to Ff.},
	keywords = {ALPHA-HELIX, COAT PROTEIN, ELECTRON-DENSITY, FIBER DIFFRACTION DATA, fibre diffraction, MEMBRANE-PROTEIN, models, MOLECULAR-STRUCTURE DETERMINATION, NMR-SPECTROSCOPY, PF1, RESOLUTION, SOLID-STATE NMR, STATE, XPLOR-NIH},
	isbn = {0175-7571},
	url = {<Go to ISI>://000256823000038},
	author = {Straus, S. K. and Scott, W. R. P. and Marvin, D. A.}
}
@article {1063,
	title = {Can PISEMA experiments be used to extract structural parameters for mobile beta-barrels?},
	journal = {Journal of Biomolecular Nmr},
	volume = {32},
	number = {2},
	year = {2005},
	note = {ISI Document Delivery No.: 948CRTimes Cited: 4Cited Reference Count: 42},
	month = {Jun},
	pages = {101-111},
	type = {Article},
	abstract = {The effect of mobility on N-15 chemical shift/N-15-H-1 dipolar coupling (PISEMA) solid state NMR experiments applied to macroscopically oriented beta-barrels is assessed using molecular dynamics simulation data of the NalP autotransporter domain embedded in a DMPC bilayer. In agreement with previous findings for alpha-helices, the fast librational motion of the peptide planes is found to have a considerable effect on the calculated PISEMA spectra. In addition, the dependence of the chemical shift anisotropy (CSA) and dipolar coupling parameters on the calculated spectra is evaluated specifically for the beta-barrel case. It is found that the precise choice of the value of the CSA parameters sigma(11), sigma(22) and sigma(33) has only a minor effect, whereas the choice of the CSA parameter theta shifts the position of the peaks by up to 20 ppm and changes the overall shape of the spectrum significantly. As was found for alpha-helices, the choice of the NH bond distance has a large effect on the dipolar coupling constant used for the calculations. Overall, it is found that the alternating beta-strands in the barrel occupy distinct regions of the PISEMA spectra, forming patterns which may prove useful in peak assignment.},
	keywords = {ANGLE-SPINNING NMR, ASSIGNMENT, COAT PROTEIN, CONSTRAINTS, DOMAIN, HELICAL WHEELS, MEMBRANE-PROTEINS, mobility of membrane beta-barrels, MOLECULAR-DYNAMICS SIMULATIONS, mosaic spread, PISEMA, SOLID-STATE NMR, SPECTROSCOPY, time averaging},
	isbn = {0925-2738},
	url = {<Go to ISI>://000230694100001},
	author = {Bleile, D. W. and Scott, W. R. P. and Straus, S. K.}
}
@article {744,
	title = {Assessing the effects of time and spatial averaging in N-15 chemical shift/N-15-H-1 dipolar correlation solid state NMR experiments},
	journal = {Journal of Biomolecular Nmr},
	volume = {26},
	number = {4},
	year = {2003},
	note = {ISI Document Delivery No.: 686MATimes Cited: 30Cited Reference Count: 51},
	month = {Aug},
	pages = {283-295},
	type = {Article},
	abstract = {The effect of time and spatial averaging on N-15 chemical shift/H-1-N-15 dipolar correlation spectra, i.e., PISEMA spectra, of alpha-helical membrane peptides and proteins is investigated. Three types of motion are considered: (a) Librational motion of the peptide planes in the alpha-helix; (b) rotation of the helix about its long axis; and (c) wobble of the helix about a nominal tilt angle. A 2ns molecular dynamics simulation of helix D of bacteriorhodopsin is used to determine the effect of librational motion on the spectral parameters. For the time averaging, the rotation and wobble of this same helix are modelled by assuming either Gaussian motion about the respective angles or a uniform distribution of a given width. For the spatial averaging, regions of possible N-15 chemical shift/H-1-N-15 dipolar splittings are computed for a distribution of rotations and/or tilt angles of the helix. The computed spectra show that under certain motional modes the N-15 chemical shift/H-1-N-15 dipolar pairs for each of the residues do not form patterns which mimic helical wheel patterns. As a result, the unambiguous identification of helix tilt and helix rotation without any resonance assignments or on the basis of a single assignment may be difficult.},
	keywords = {averaging, COAT PROTEIN, GRAMICIDIN CHANNEL, ION-CHANNEL, LIPID BILAYERS, MEMBRANE-PROTEIN STRUCTURE, mobility of membrane helices, MOLECULAR-DYNAMICS SIMULATION, mosaic spread, NUCLEAR-MAGNETIC-RESONANCE, PHOSPHOLIPID-BILAYER, PISA wheels, PISEMA, SPIN-EXCHANGE, time, TRANSMEMBRANE DOMAIN},
	isbn = {0925-2738},
	url = {<Go to ISI>://000183324500001},
	author = {Straus, S. K. and Scott, W. R. P. and Watts, A.}
}
