X-ray long spacing

Figure 3. Two-dimensional, hexagonal structure of the middle mesophase in relation to the measured x-ray long spacing, d...

Figure 3. X-ray long spacings (A) of systems of cetyl-trimethylammonium bromide and water as a function of the ratio gram water/gram association colloid (8)...

Figure 4. X-ray long spacings of a 69.6% dimethyl-dodecylamine oxide in deuterium oxide solution as a function of temperature (9)...

Fig. 2.5. X-ray long spacings at 20 C as a function of water/lipid weight ratio, (l-c)/c. Derived from the low-angle diffraction of dipalmitoyl phosphatidylglycerol multibilayers at pH 8.0, 1.5 M KCl/50 mM Tris (o—o) and pH 1.5, 1.5 M KCl/HCl ----------------A ) (Watts et al., 1981).

X-ray structures of mitochondrial 6ci complexes from three different sources (113, 124, 125) have found the b- and c-type hemes at roughly identical positions, whereas the Rieske protein was seen in different places as a function of crystal space group and presence or absence of inhibitors of the enzyme. This fact was interpreted to suggest a long-range conformational movement of the Rieske protein during turnover of the complex. The range of observed positions of the Rieske protein indicated that the soluble domain can move like a... 

Fig. 7). That space is enough to accommodate just one monolayer of B DNA. Small-angle x-ray scattering also detected long-range order in the position of the axes of the DNA helices. 

X-ray diffraction from cast films provide useful information of bilayer structure. Periodic peaks in small and middle-angle diffraction from cast films on glass plates are attributed to the reflections from (h, 0,0) planes of the multiple lamella structure. The spacing of higher order reflections (h > 1) satisfies with numerical relation of 1 / h of the long period calculated from the first order reflection =1), which is equivalent to the bilayer thickness. Every cast film measured in this experiment showed more than 6 reflection peaks. 

In the Z-type deposition film, however, the long spacing of 7.2 nm did not agree with the predicted value of 3.9 nm rather, it was the same value as that of the Y-type deposition film. This result demonstrates that the Z-type film does not possess the Z-type layer structure but the Y-type layer structure. It should be assumed that the molecules were turned over in the deposition process and formed the Y-type layer structure, since the Z-type layer structure in which a hydrophilic group touches on a hydrophobic group is unstable. The conclusion from the examination of long spacings well supports molecular orientations in the LB films determined from the linear Stark effect measurements. From the linear Stark effect and the X-ray diffraction measurements, it is demonstrated that the hetero Y-type deposition method is useful for fabrication of stable noncentrosymmetric LB films. 

Fig. 1. Cross-/] structure of amyloid fibrils. (A) Cartoon representation of a cross-/] X-ray diffraction pattern. The defining features are a meridional reflection at 4.7 A and an equatorial reflection on the order of 10 A. The 4.7-A reflection is generally much brighter and sharper than the reflection at 10 A. (B) The cross-/] core structure of amyloid fibrils. Parallel /(-sheets are depicted, but the structure could equivalendy be composed of antiparallel /(-sheets or a mix of parallel and antiparallel. The 4.7-A spacing of /(-strands within each /(-sheet is parallel to the long fibril axis. The depicted 10-A sheet-to-sheet spacing actually ranges from about 5 to 14 A (Fandrich and Dobson, 2002), depending on the size and packing of amino acid side chains. Amyloid fibrils have diameters on the order of 100 A.

Figure 5.8 A Debye-Scherrer powder camera for X-ray diffraction. The camera (a) consists of a long strip of photographic film fitted inside a disk. The sample (usually contained within a quartz capillary tube) is mounted vertically at the center of the camera and rotated slowly around its vertical axis. X-rays enter from the left, are scattered by the sample, and the undeflected part of the beam exits at the right. After about 24 hours the film is removed (b), and, following development, shows the diffraction pattern as a series of pairs of dark lines, symmetric about the exit slit. The diffraction angle (20) is measured from the film, and used to calculate the d spacings of the crystal from Bragg s law.

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