Small Angle Scattering

Hösemann, R.; Schönfeld, A.; Wilke, W.

doi:10.1016/b978-0-08-017543-0.50005-5

Cited by 5 publications

(4 citation statements)

References 375 publications

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“…Since insensity measurements must be terminated when the excess intensity becomes too small to measure with precision the integral c'dn be evaluated if the outer part of the scattering curve exhibits a Porod region in which f varies with K 3 . If there is some degree of internal order in the scattering particle the scattered intensity is written = the volume fraction of solvent, was found to be 0.0475 nm-', so that the total surface area per molecule S4, SV, is 565 nm2 [42]. The molecular parameters derived from low-angle X-ray scattering of protein S4 in solution are listed in Table 2.…”

Section: Low-angle X-ray Scatteringmentioning

confidence: 99%

Geometry of the Protein S4 from Escherichia coli Ribosomes

Paradies

Franz²

1976

European Journal of Biochemistry

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The shape of protein S4 from Escherichia coli ribosomes in solution was determined by hydrodynamic methods and low-angle X-ray scattering. The molecular weight of 24000 determined by low-angle X-ray scattering is within 3 % of that found by sedimentation equilibrium analysis and 8 of that determined by amino acid sequence work. The radius of gyration of 3.36 nm. the radius of gyration of the cross section of 0.41 nm and the hydrodynamic studies revealed that protein S4 is not spherical, but rather has a markedly extended shape. Calculations of different conformations, e.g. random coil, based on the parameters evaluated from hydrodynamic methods, revealed a rod-like structure of S4 with a length of 14 nm and a diameter of 1 nm. This is supported by a model of an equivalent scattering particle of uniform density based on all parameters obtained in this study.Physiochemical characterizations of ribosomal proteins, especially those which specifically bind to 23-S, 16-S or 5-S RNA, are of importance for studies on protein-RNA interactions and on the topography of the ribosoinal particle. Although the chemical and immunological properties of the isolated proteins [l -51 have been studied intensively, very little is known about the shape of the individual proteins, e.g. if they are globular or highly asymmetric. Only the shapes of the proteins L7 and L12 have recently been determined [6].Protein S4, of which the primary sequence has been determined [7], is one of the most interesting proteins in the Escherichiu coli 30-S ribosomal subunits. It binds specifically to the 16-S RNA [8], and details of the interaction between proteins S4 and 16-S RNA have been studied [9-131. Furthermore, mutants with drastically altered S4 proteins, whose binding to 16-S RNA can be impaired, have been investigated [14-211. Information on the shape of protein S4 would help to understand its role in protein-RNA interactions.In the present study attempts were made to determine the shape of protein S4 in solution, e . g . reconstitution buffer [22]. The gross conformation of the S4 molecule in solution was determined by different techniques, of which low-angle X-ray scattering proved to be the most useful. Moreover, several hydrodynamic methods revealed that S4 has a markedly extended shape. MATERIALS AND METHODS Isolation of Protein S4

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Section: Low-angle X-ray Scatteringmentioning

confidence: 99%

Geometry of the Protein S4 from Escherichia coli Ribosomes

Paradies

Franz²

1976

European Journal of Biochemistry

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“…Core-fibril thicknesses and lattice distortions can be determined using the method introduced by Hosemann and Wilke [20]. The integral half widths of the …”

Section: Resultsmentioning

confidence: 99%

X-ray investigations of the formation of core-fibrils crystallized out of the oriented melt

Wenig

Schöller

1988

Colloid & Polymer Sci

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Crystallization models for the formation of core-fibrils crystallized from the oriented melt are discussed by comparing results from X-ray experiments with theoretical predictions. Two sets of polymer blends, the systems iPP/PB-1 and iPP/aPP have been measured. From wide angle X-ray scattering, the thicknesses of the core-fibrils, lattice distortions, and unit-cell parameters have been determined. Interface distribution functions have been used to evaluate the axial morphology of the fibers from meridional small angle X-ray scattering curves. It appears that the morphological predictions made by the crystallization models of Pennings and of Hoffman cannot be confirmed by the experimental findings. The diffusion model proposed by Petermann partially describes the morphological properties of the core-fibrils.

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“…Such an effect has frequently been found after a drawing of polymer materials. [43][44][45][46][47][48][49] MFC7 is very close to local fiber symmetry. Thus, application of XSF-CT results in almost perfect reconstruction of the nanostructure.…”

Section: Discussionmentioning

confidence: 99%

SAXS-Fiber Computer Tomography. Method Enhancement and Analysis of Microfibrillar-Reinforced Composite Precursors from PEBA and PET

et al. 2008

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The nanostructure gradient along the fiber radius inside polymer strands is uncovered by smallangle X-ray scattering (SAXS) microbeam-scanning experiments and X-ray scattering fiber computer-tomography (XSF-CT) analysis. We notice restricted visibility of scattering features within the series of patterns. The reason is violation of local fiber symmetry (LFS) in the irradiated volume elements (voxels). For its theoretical treatment, a set of elementary topologies (tangential grain, radial grain) is introduced. Systematic aberrations (ultrareconstruction, infrareconstruction) generated by tomographic reconstruction of affected series are described. A concept for handling and utilization of these aberrations for nanostructure analysis is devised. Precursors of polymer microfibrillar-reinforced composites (MFC) containing poly(ether)-block-amide (PEBA) and poly(ethylene terephthalate) (PET) with varying cold-draw ratio are studied. We compare results from a direct analysis of the smeared measured patterns to results obtained after tomographic reconstruction and fathom the power of reconstruction methods. Ideas for advanced practical applications of the XSF-CT method are discussed.

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Small Angle Scattering

Cited by 5 publications

References 375 publications

Geometry of the Protein S4 from Escherichia coli Ribosomes

Geometry of the Protein S4 from Escherichia coli Ribosomes

X-ray investigations of the formation of core-fibrils crystallized out of the oriented melt

SAXS-Fiber Computer Tomography. Method Enhancement and Analysis of Microfibrillar-Reinforced Composite Precursors from PEBA and PET

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