@article {2415,
	title = {X-ray Crystal Analysis of a TASP: Structural Insights of a Cavitein Dimer},
	journal = {Journal of the American Chemical Society},
	volume = {131},
	number = {21},
	year = {2009},
	note = {ISI Document Delivery No.: 451QOTimes Cited: 0Cited Reference Count: 75Freeman, Jon O. Lee, Woo Cheol Murphy, Michael E. P. Sherman, John C.},
	month = {Jun},
	pages = {7421-7429},
	type = {Article},
	abstract = {Cavitein Q4 is a template assembled synthetic protein designed for X-ray crystallographic analysis. It is based on a previous monomeric helical bundle cavitein (N1GG) that consists of four identical parallel helical peptides. Crystals that were grown in the presence of bromide ions were used to solve the initial phases via single-wavelength anomalous dispersion (SAD). A 1.4 angstrom resolution data set was then refined starting with the SAD phases to provide the crystal structure of cavitein Q4. The crystal structure revealed cavitein Q4 as an asymmetric dimer, although the cavitein appears to be largely monomeric in solution. A comparative analysis is carried out to discern any intrinsic differences between Q4 and its parent cavitein N1GG. We present herein the first X-ray crystal structure of a TASP system and relate this structure to the solution data for both Q4 and its parent N1GG.},
	keywords = {4-HELIX BUNDLE, ALPHA-HELICES, ANALYTICAL, ANION-BINDING, ASSEMBLED SYNTHETIC PROTEINS, DE-NOVO PROTEINS, NATIVE-LIKE STRUCTURE, PEPTIDE-CAVITANDS, PROTEINS, SELF-ASSOCIATION, ULTRACENTRIFUGATION, UPPER RIM},
	isbn = {0002-7863},
	url = {<Go to ISI>://000266484900042},
	author = {Freeman, J. O. and Lee, W. C. and Murphy, M. E. P. and Sherman, J. C.}
}
@article {1484,
	title = {Molecular structure of fd (f1, M13) filamentous bacteriophage refined with respect to X-ray fibre diffraction and solid-state NMR data supports specific models of phage assembly at the bacterial membrane},
	journal = {Journal of Molecular Biology},
	volume = {355},
	number = {2},
	year = {2006},
	note = {ISI Document Delivery No.: 999EPTimes Cited: 30Cited Reference Count: 84},
	month = {Jan},
	pages = {294-309},
	type = {Article},
	abstract = {Filamentous bacteriophage (Inovirus) is a simple and well-characterized model system. The phage particle, or virion, is about 60 A in diameter and several thousand angstrom units long. The virions are assembled at the bacterial membrane as they extrude out of the host without killing it, an example of specific transport of nucleoprotein assemblages across membranes. The Ff group (fd, f1. and M13) has been especially widely studied. Models of virion assembly have been proposed based on a molecular model of the fd virion derived by X-ray fibre diffraction. A somewhat different model of the fd virion using solid-state NMR data has been proposed, not consistent with these models of assembly nor with the X-ray diffraction data. Here we show that reinterpreted NMR data are also consistent with the model derived from X-ray fibre diffraction studies, and discuss models of virion assembly. (c) 2005 Elsevier Ltd. All rights reserved.},
	keywords = {ALPHA-HELICES, ALPHA-HELIX, ATOMIC REFINEMENT, fibre diffraction, filamentous bacteriophage, INOVIRUS, MAJOR COAT PROTEIN, MEMBRANE, ORIENTATIONAL RESTRAINTS, PF1 BACTERIOPHAGE, PISEMA, PROTEINS, RESOLUTION, SINGLE-STRANDED-DNA, VIRION, VIRUS},
	isbn = {0022-2836},
	url = {<Go to ISI>://000234371900012},
	author = {Marvin, D. A. and Welsh, L. C. and Symmons, M. F. and Scott, W. R. P. and Straus, S. K.}
}
@article {3799,
	title = {Characterization of a buried neutral histidine residue in Bacillus circulans xylanase: NMR assignments, pH titration, and hydrogen exchange},
	journal = {Protein Science},
	volume = {5},
	number = {11},
	year = {1996},
	note = {ISI Document Delivery No.: VQ786Times Cited: 41Cited Reference Count: 63},
	month = {Nov},
	pages = {2319-2328},
	type = {Article},
	abstract = {Bacillus circulans xylanase contains two histidines, one of which (His 156) is solvent exposed, whereas the other (His 149) is buried within its hydrophobic core. His 149 is involved in a network of hydrogen bonds with an internal water and Ser 130, as well as a potential weak aromatic-aromatic interaction with Tyr 105. These three residues, and their network of interactions with the bound water, are conserved in four homologous xylanases. To probe the structural role played by His 149, NMR spectroscopy was used to characterize the histidines in BCX. Complete assignments of the H-1, C-13, and N-15 resonances and tautomeric forms of the imidazole rings were obtained from two-dimensional heteronuclear correlation experiments. An unusual spectroscopic feature of BCX is a peak near 12 ppm arising from the nitrogen bonded H-1(epsilon 2) of His 149. Due to its solvent inaccessibility and hydrogen bonding to an internal water molecule, the exchange rate of this proton (4.0 X 10(-5) s(-1) at pH* 7.04 and 30 degrees C) is retarded by > 10(6)-fold relative to an exposed histidine. The pK(a) of His 156 is unperturbed at similar to 6.5, as measured from the pH dependence of the N-15- and H-1-NMR spectra of BCX. In contrast, His 149 has a pK(a) < 2.3, existing in the neutral (NH)-H-epsilon 2 tautomeric state under all conditions examined. BCX unfolds at low pH and 30 degrees C, and thus His 149 is never protonated significantly in the context of the native enzyme. The structural importance of this buried histidine is confirmed by the destablizing effect of substituting a phenylalanine or glutamine at position 149 in BCX.},
	keywords = {ACTIVE-SITE, ALPHA-HELICES, AQUEOUS-SOLUTION, CHEMICAL-SHIFTS, ESCHERICHIA-COLI, GLYCOSYL HYDROLASES, H-1-NMR SPECTRUM, HYDROGEN-DEUTERIUM EXCHANGE, IMIDAZOLE, internal water, L-ALA-OH, NUCLEAR MAGNETIC-RESONANCE, pH titration, pK(alpha), PROTEIN HYDRATION, protein stability},
	isbn = {0961-8368},
	url = {<Go to ISI>://A1996VQ78600018},
	author = {Plesniak, L. A. and Connelly, G. P. and Wakarchuk, W. W. and McIntosh, L. P.}
}
