Cryo-electron microscopy

A labeling efEciency of 11% was estimated from spectroscopic measurements. The tetra-iridium cluster was clearly visualized in three-dimensional density maps at good resolution despite the relatively low site occupancy. Interestingly, cysteine residues inaccessible to undecagold reagent were reached with the much smaller tetra-iridium complex 45 [81]. 

The reaction of the gold(III) organometallic complex 46 with BSA has been studied by a variety of techniques. 

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Berriman J and Unwin N 1994 Analysis of transient structures by cryo-electron microscopy combined with rapid mixing of spray droplets Ultramicroscopy 56 241-52... 

Chen, S. et al. Eocation of a folding protein and shape changes in GroEL-GroES complexes imaged by cryo-electron microscopy. Nature 371 261-264, 1994. 

Ryanodine Receptor. Figure 1 Three-dimensional architecture of the RyR1 by cryo-electron microscopy, (a), top view (from the T-tubule) (b), bottom view (from the SR lumen) (c), side view (parallel to the SR membrane). The binding sites of FKBP12, apo-CaM and Ca -CaM are indicated in the side view. Courtesy of Dr. M. Samso (modified from Samso etal. (2005) Nat Struct Mol Biol 12 539-544). 

The three-dimensional structure of the sodium channel (from electric eel) was determined at 19-A resolution using cryo-electron microscopy and single-particle image analysis. The sodium channel has a bell-shaped outer surface of 135 A in height, 100 A in side length at the square bottom, and 65 A in diameter of the spherical top. An interesting finding is that there are several inner cavities connected to outer orifices. 

Tama, F. Valle, M. Frank, J. Brooks, C.L., Dynamic reorganization of the functionally active ribosome explored by normal mode analysis and cryo-electron microscopy, Proc. Natl Acad. Sci. USA 2003,100, 9319-9323... 

Jimenez, J. L., Tennent, G., Pepys, M., and Saibil, H. R. (2001). Structural diversity of ex vivo amyloid fibrils studied by cryo-electron microscopy. /. Mol. Biol. 311, 241-247. 

Saibil, H. R. (2000). Macromolecular structure determination by cryo-electron microscopy. Acta Crystallogr. D Biol. Crystalhgr. 56(Pt. 10), 1215-1222. 

Sass, H. J., Btlldt, G., Beckmann, E., Zemlin, F., Van Heel, M., Zeitler, E., Rosenbusch, J. P., Dorset, D. L., and Massalski, A. (1989). Densely packed beta-structure at the protein-lipid interface of porin is revealed by high-resolution cryo-electron microscopy. J. Mol. Biol. 209,171-1... 

Images obtained by cryo electron microscopy should in principle be able to distinguish between the structural features proposed by the different models mentioned above [16]. The micrographs show a zig-zag motif at lower salt concentrations and they indicate that the chromatin fiber becomes more and more compact when the ionic strength is raised towards the physiological value (i.e., about 150 mM monovalent ions). 

Conway, J. R, et al. (1997). VisuaUzation of a 4-hehx bundle in the hepatitis B virus capsid by cryo-electron microscopy. Nature 386,91-94. 

Figure 30-17 (A) Two-dimensional map of the 260-kDa a subunit of the voltage-gated Na+ channel from the electric eel Electrophorus e/ecfns.438 441 (B) Image of the sodium channel protein obtained by cryo-electron microscopy and image analysis at 1.9 nm resolution. In this side view the protein appears to be bell-shaped with a height of 13.5 nm, a square bottom (cytoplasmic surface) 10 nm on a side, and a hemispherical top with a diameter of 6.5 nm. (C) Bottom view of the protein. (D) Axial section which cuts the bottom, as viewed in (C), approximately along a diagonal. From Sato et al.438 Notice the cavities (dark) and domain structures (light). The black arrow marks a constriction between upper (extracelllar) and lower (cytoplasmic) cavities. White lines indicate approximate position of the lipid bilayer. From Sato et al.i38 Courtesy of Chikara Sato.

Rao, S., Poojary, M., Elliott, B., Melanson, L., Oriel, B., and Cohen, C. (1991). Fibrinogen structure in projection at 18 A resolution. Electron density by co-ordinated cryo-electron microscopy and X-ray crystallography. J. Mol. Biol. 222, 89-98. 

In a recent extensive study, the structural polymorphism of DNA/RPR120535 complexes has been studied by X-ray diffraction and cryo-electron microscopy. Monovalent salts and temperature effects have been analyzed. Depending on the treatment applied to the lipid solution prior to DNA addition, two types of... 

In this chapter, we provide an overview of our recent efforts to develop a fundamental science base for the design and preparation of optimal lipid-based carriers of DNA and siRNA for gene therapy and gene silencing. We employ synthesis of custom multivalent lipids, synchrotron X-ray diffraction (XRD) techniques, optical and cryo-electron microscopy, as well as biological assays in order to correlate the structures, chemical, and biophysical properties of cationic liposome (CL)-NA complexes to their biological activity and to clarify the interactions between CL-NA complexes and cellular components. Earlier work has been reviewed elsewhere [1-7] and will not be covered exhaustively here. 

Structural elements that interact with the microtubule surface have been identified by the effect of point mutations (Woehlke et al, 1997) and by fitting crystal structures of kinesin motor domains to low-resolution electron density maps obtained by cryo-electron microscopy of microtubules... 

So far, crystallization of a-LTX has not been reported. However, the toxin has been successfully studied by cryo-electron microscopy (cryo-EM) (Orlova et al. 2000),... 

Cryo-Electron Microscopy for Biological Structure Determinations... 

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