Quick Freeze Deep Etch

Figure 5.25 AFM images of intermediate stmctures in self-assembly of peptide KFE8 in aqueous solution deposited on freshly cleaved mica surface (a) 8 min after preparation of solution. Inset electron micrograph of sample of peptide solution obtained using quick-freeze deep-etch technique (b) 35 min, (c) 2 h, and (d) 30 h after preparation. Reprinted with permission from Ref. 110. Copyright 2002 by the American Chemical Society.

Figure 5.26 TEM image of surfactant-like peptide A6D dissolved in water (4.3 mM at pH 7) obtained using quick-freeze deep-etch technique. Image shows dimensions, 30-50 nm in diameter with openings of nanotube ends (arrows). Inset Opening ends in more detail. Reprinted with permission from Ref. 112. Copyright 2002 by the National Academy of Sciences, U.S.A.

In tissues, microfibrils form loosely packed parallel bundles. X-ray fiber diffraction of hydrated zonular microfibril bundles identified one-third-staggered junctions that may modulate force transmission (Wess et al., 1998a), and quick-freeze deep-etch analysis of zonules has identified molecular links between microfibrils (Davis et al., 2002). 

Hanson PI, Roth R, Morisaki H, Jahn R, Heuser JE (1997) Structure and conformational changes in NSF and its membrane receptor complexes visualized by quick-freeze/deep-etch electron microscopy. Cell 90 523-35... 

Arima T, Kuraoka A, Toriya R, Shibata Y, Uemura T. 1991. Quick-freeze, deep-etch visualization of the cytoskeletal spring ofcochlear outer hair cells. Cell Tissue Res 263 91-97. 

Katayama, E., Shiraishi, T, Oosawa, K., Baba, N. and Aizawa, S.-I. (1996). Geometry of the flagellar motor in the cytoplasmic membrane of Salmonella typhimurium as determined by stereo-photogrammetry of quick-freeze deep-etch rephca images./. Mol. Biol. 255, 458 75. 

H. Gong, J. Ruberti, D. Overby, M. Johnson, T.F. Freddo, A new view of the human trabecular meshwork using quick-freeze, deep-etch electron microscopy, Exp. Eye Res. 75 (2002) 347-358. 

The homogeneity and size of the supramolecular assembly were sequence-sensitive peptides of the same length behaved differently when they had different polar head or hydrophobic tail sequences. Such phenomena have been described theoretically and experimentally in other amphiphilic systems. The shape and size of the assemblies are ultimately dependent on the size and geometry of their constituents [ 71 ]. In order to visualize the structures in solution, we utilized the transmission electron microscope with the quick-freeze/deep-etch method for sample preparation [72], to preserve the structures that formed in solution for electron microscopy. We observed discrete nanotubes and vesicles... 

Fig. 5 A Molecular models of surfactant peptides V6D and K2V6. These peptides have hydrophilic heads either negatively charged aspartic acid or positively charged lysine with hydrophobic valine tails [13-15]. a V6D in nanotuhe form. Billions of these molecules self-assemhle to sequester the valine tails from water in b vesicle form or c nanotuhe form with positively charged heads. These nanostructures are rather dynamic undergoing assembly and disassembly. Color code green-hydrophobic tails, red-aspartic acid, and blue-lysine. B Quick-freeze/deep-etch transmission electron micrographs of structures from surfactant peptides, a The nanotubes are clearly represented, with a diameter 30-50 nm. b The nanotubes and vesicles are visible in the same frame suggesting that these structures are quite dynamic. It is plausible that the vesicles may be budded out from the nanotubes and/or they may fuse to form nanotubes in a reversible manner [IBIS]. The diameter of these nanostructures is 30-50 nm. c Phosphor-serine surfactant peptides form nano Q-tips...

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