Structural analysis of leuconostoc dextrans containing 3-O-α-d-glucosylated α-d-glucosyl residues in both linear-chain and branch-point positions, or only in branch-point positions, by methylation and by 13C-N.M.R. spectroscopy

[Pt(C3H10N2)2][Pt(C3H10N2)2Br2](ClO4)4 crystallizes as flat orthorhombic needles with cell dimensions: a = 7.74(1); b = 11.14(2); c = 19.42(3) Å, Z = 1. Since rotation photographs showed diffuse patterns corresponding to odd values of k without any Bragg reflections, the subcell for which b = 5.57(1) Å was adopted for the structural analysis; it has systematic absences consistent with space groups Pc 2 a and Pcma; the structure was refined in both space groups by least squares and difference Fourier syntheses to R = 0.062 in Pc 2a and R = 0.064 in Pcma. A final decision between the two space groups proved to be impossible within the scope of the experiment. An analysis of the “diffuse” layers reveals that the bridging bromines vibrate in a one-dimensional collective mode within a lattice of “uniform”, fixed platinum cations.

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Structure of the Linear-Chain Mixed Valence Compound Bis(l,3-diaminopropane)platinum(II)bis(l,3-diaminopropane)- diiodoplatinum(IV)tetraperchlorate

Zeitschrift für Naturforschung B ◽

10.1515/znb-1984-0213 ◽

1984 ◽

Vol 39 (2) ◽

pp. 197-200 ◽

Cited By ~ 2

Author(s):

Mario Cannas ◽

Giaime Marongiu ◽

Heimo J. Keller ◽

Barbara Müller ◽

Reinhold Martin

Keyword(s):

Structural Analysis ◽

Crystal Structures ◽

Satisfactory Agreement ◽

Title Compound ◽

Linear Chain ◽

Mixed Valence ◽

Space Groups ◽

Compound C ◽

Mixed Valence Compound

The title compound C12H49Cl4I2N8O 16Pt2, Mr 1314.1, is monoclinic P 21 (from structural analysis), a = 8.74(1), b = 11.36(1), c = 8.63(1), β = 107.6(5), V = 817 Å3, Z = 1, Dm (flotation) = 2.65 g cm-3, Dc = 2.66 g cm-3, MoKɑ λ = 0.71069, μ = 110.7 cm-1, R = 0.063 for 1068 observed reflections. Rotation photographs show diffuse patterns corresponding to odd values of k together with weak Bragg reflections. Refinement of diffractometer data was carried out in space groups Pm, P21/m and P21; both refinement in Pm and P21 give satisfactory agreement and lead to very similar crystal structures

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Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077268 ◽

1983 ◽

Vol 41 ◽

pp. 738-739

Author(s):

W. H. Wu ◽

R. M. Glaeser

Keyword(s):

Electron Microscopy ◽

Surface Layer ◽

Structural Analysis ◽

High Resolution ◽

Low Dose ◽

High Resolution Electron Microscopy ◽

Optical Diffraction ◽

Surface Layer Protein ◽

Morphological Unit ◽

Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

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RNA polymerase: Preparation and structural analysis of helical polymers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011091x ◽

1984 ◽

Vol 42 ◽

pp. 152-153

Author(s):

E. Loren Buhle ◽

Pamela Rew ◽

Ueli Aebi

Keyword(s):

Structural Analysis ◽

Rna Polymerase ◽

Molecular Level ◽

X Ray Diffraction ◽

Helical Polymers ◽

X Ray ◽

E Coli ◽

The Past ◽

Ordered Arrays ◽

Low Ionic Strength

While DNA-dependent RNA polymerase represents one of the key enzymes involved in transcription and ultimately in gene expression in procaryotic and eucaryotic cells, little progress has been made towards elucidation of its 3-D structure at the molecular level over the past few years. This is mainly because to date no 3-D crystals suitable for X-ray diffraction analysis have been obtained with this rather large (MW ~500 kd) multi-subunit (α2ββ'ζ). As an alternative, we have been trying to form ordered arrays of RNA polymerase from E. coli suitable for structural analysis in the electron microscope combined with image processing. Here we report about helical polymers induced from holoenzyme (α2ββ'ζ) at low ionic strength with 5-7 mM MnCl2 (see Fig. 1a). The presence of the ζ-subunit (MW 86 kd) is required to form these polymers, since the core enzyme (α2ββ') does fail to assemble into such structures under these conditions.

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Interpreting HVEM of muscle-cell impulse networks

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012103x ◽

1992 ◽

Vol 50 (1) ◽

pp. 126-127

Author(s):

Paul DeCosta ◽

Kyugon Cho ◽

Stephen Shemlon ◽

Heesung Jun ◽

Stanley M. Dunn

Keyword(s):

Structural Analysis ◽

Muscle Cell ◽

Electron Micrographs ◽

Relative Size ◽

Automatic Classification ◽

Nerve Fibers ◽

Analysis Algorithm ◽

Structural Networks

Introduction: The analysis and interpretation of electron micrographs of cells and tissues, often requires the accurate extraction of structural networks, which either provide immediate 2D or 3D information, or from which the desired information can be inferred. The images of these structures contain lines and/or curves whose orientation, lengths, and intersections characterize the overall network.Some examples exist of studies that have been done in the analysis of networks of natural structures. In, Sebok and Roemer determine the complexity of nerve structures in an EM formed slide. Here the number of nodes that exist in the image describes how dense nerve fibers are in a particular region of the skin. Hildith proposes a network structural analysis algorithm for the automatic classification of chromosome spreads (type, relative size and orientation).

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Fractionation of polymethylene chains: An electron crystallographic investigation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100145315 ◽

1986 ◽

Vol 44 ◽

pp. 794-795

Author(s):

Douglas L. Dorset

Keyword(s):

Cross Section ◽

Binary Systems ◽

Linear Chain ◽

Pure Component ◽

Organic Substrates ◽

Crystallographic Investigation ◽

X Ray Diffraction ◽

X Ray ◽

Molecular Sizes ◽

The Stability

A variety of linear chain materials exist as polydisperse systems which are difficultly purified. The stability of continuous binary solid solutions assume that the Gibbs free energy of the solution is lower than that of either crystal component, a condition which includes such factors as relative molecular sizes and shapes and perhaps the symmetry of the pure component crystal structures.Although extensive studies of n-alkane miscibility have been carried out via powder X-ray diffraction of bulk samples we have begun to examine binary systems as single crystals, taking advantage of the well-known enhanced scattering cross section of matter for electrons and also the favorable projection of a paraffin crystal structure posited by epitaxial crystallization of such samples on organic substrates such as benzoic acid.

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Field ion microscope investigations of atomic processes at surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153117 ◽

1989 ◽

Vol 47 ◽

pp. 228-229

Author(s):

G. L. Kellogg ◽

P. R. Schwoebel

Keyword(s):

Single Crystal ◽

Crystal Surface ◽

Linear Chain ◽

Atom Probe ◽

Nucleation And Growth ◽

Single Atom ◽

Initial Structure ◽

Atomic Processes ◽

Single Crystal Surfaces ◽

Field Ion Microscope

Although no longer unique in its ability to resolve individual single atoms on surfaces, the field ion microscope remains a powerful tool for the quantitative characterization of atomic processes on single-crystal surfaces. Investigations of single-atom surface diffusion, adatom-adatom interactions, surface reconstructions, cluster nucleation and growth, and a variety of surface chemical reactions have provided new insights to the atomic nature of surfaces. Moreover, the ability to determine the chemical identity of selected atoms seen in the field ion microscope image by atom-probe mass spectroscopy has increased or even changed our understanding of solid-state-reaction processes such as ordering, clustering, precipitation and segregation in alloys. This presentation focuses on the operational principles of the field-ion microscope and atom-probe mass spectrometer and some very recent applications of the field ion microscope to the nucleation and growth of metal clusters on metal surfaces.The structure assumed by clusters of atoms on a single-crystal surface yields fundamental information on the adatom-adatom interactions important in crystal growth. It was discovered in previous investigations with the field ion microscope that, contrary to intuition, the initial structure of clusters of Pt, Pd, Ir and Ni atoms on W(110) is a linear chain oriented in the <111> direction of the substrate.

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