Metal shadowing

Glenny JR. Rotary metal shadowing for visualizing rod-shaped proteins, in Electron Microscopy in Molecular Biology. A Practical Approach (Sommerville J, Scheer U, eds.), IRL Press, Oxford, UK, 1987, pp. 167-178. 

Fig. 1. Structure of amyloid fibrils formed by the human amylin peptide. Negatively stained (A) and metal shadowed (B) fibrils formed by human amylin (adapted from Goldsbury et al., 2000a). (C) A human amylin fibril model formed by three protofibrils having a superpleated /i-structure (adapted from Kajava et al., 2005). Only Ca traces of the polypeptide chains are shown. (D) Atomic model of the cross-/ motif formed by the human amylin peptide (adapted from Kajava et al, 2005). Scale bar, 100 nm (A and B).

Electron Microscopy can be used for resolution of smaller objects the practical limit of resolution being a few angstrom units. Electron Microscopy has been used in the study of the morphology of crystalline polymers. The usual techniques of replication, heavy-metal shadowing, and solvent etching are widely used. The direct observation of thin specimens, like polymer single crystals, is also possible and permits the observation of the electron-diffraction pattern of some specimen area, which is invaluable for... 

Fig. 16a,b. a Surface pressure - area/molecule isotherms of Langmuir films of (PS)2so (RPVP+I )24o, where the P4VP block was quaternized with different n-alkyliodides R = Cj, C4, Q, Cio- b Metal shadowed TEM micrographs of the LB films of P(S26o-b-VP7i/C101) deposited on a carbon-coated surface at 2 mN/m from a pure water surface [149]... 

Figure 27-7 Native nuclear lamina of Xenopus oocytes. Freeze-dried metal-shadowed nuclear envelope extracted with Triton X-100, revealing the nuclear lamina meshwork partially covered with arrays of nuclear pore complexes. Inset, relatively well-preserved area of the meshwork of nearly orthogonal filaments from which pore complexes have been mechanically removed. Bar, 1 pm. From Aebi et al.121...

Fig. 1. (A) Metal-shadowed replica of partially purified glomerular basement...

Figure 15.1 Kleinschmidt metal-shadowing electron microscopy of liposome/DNA complexes. Lipid/DNA complexes were prepared with gradually increasing amounts of DOPE/DOTMA liposomes and a constant amount of DNA (3.5pg/ mL). Liposome/DNA (+/- charge) ratios were 0.2 (A), 0.4 (B), 0.6 (C), 1 (D), and 1.5 (E). The scale bar represents 0.5 pm. This figure was reproduced with permission from Gershon et al. (1993).

Kleinschmidt metal-shadowing electron microscopy of liposome/DNA complexes 276... 

Hamilton and Phelps [50] adapted the metal shadowing technique for the preparation of transparent profiles of dust particles. The process consisted of evaporating in vacuo a thin metal film in a direction normal to... 

A recent three-dimensional reconstruction from a tilted series of negatively stained and of metal-shadowed preparations of the S-layer of Methanoplanus limicola[ Q6 has shown P6 symmetry, a lattice constant of 14.7 nm, and a thickness of 4.5 mn. Chemical analysis of these S-layers revealed an apparent molecular weight of the protein of 135 kDa, and the neutral sugar content of 240 mg/g polypeptide corroborates earlier suggestions... 

Transmission electron microscopy Is also used to obtain Information about the shapes of purified viruses, fibers, enzymes, and other subcellular particles by using a technique, called metal shadowing. In which a thin layer of metal, such... 

FIG U R E 2 Metal-shadowed smooth muscle myosin in the folded and extended conformation. Upper panel At physiological ionic strength in the presence of MgATP, myosin preferentially forms a folded monomer where the tail is bent into approximately equal thirds. Note the heads often bend down toward the rod. Lower panel For comparison, extended monomers formed at high ionic strength are shown. Bar-50 nm. Reprinted from Trybus, K. M., and Lowey, S., Journal of Biological Chemistry 259, 8564-8571, 1984. 

The second method employs replication. Direct replica or two-stage replica of the free surface can be used. The free surface may be obtained, e.g., by cryofracture, chemical etching, ion bombardment, etc. Metal shadowing of the replicas with C/Pt coating is frequently used for contrast. 

A.) have been obtained both for muscle filaments and natural acto-myosin threads (Section III, 4d) only when the preparations are stained (see above), and in metal-shadowed preparations thicknesses less than 100 A. have never been found (Draper and Hodge 1949 Rozsa et al, 1950 Jakus and Hall, 1947). A comparison of purified material with muscle filaments is therefore justified only when the preparations have been subjected to the same treatment. 

Metal-shadowed threads of artificial F-actin obtained by polymerization of G-actin are 100 A. thick (Jakus and Hall, 1947 Rozsa et al., 1949), and threads of natural actomyosin appear to be about as thick, for they have a very similar sedimentation constant and a similar thickness in metal-shadowed preparations. From its thickness, the muscle filament could thus be identified with the F-actin or actomyosin thread. 

Tt is on ly after having understood the secret meaning these that the pilgrim will finally see rise, shining in the heart of the metallic shadows, the Star of Compostella, which announces the end of the golden periplus. ... 

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