Protein Chains in Wool and Epidermal Keratin IF: Structural Features and Spatial Arrangement

1988 ◽  
pp. 127-144 ◽  
Author(s):  
J. F. Conway ◽  
R. D. B. Fraser ◽  
T. P. Macrae ◽  
D. A. D. Parry
Keyword(s):  
Spatial Arrangement ◽  
Structural Features

Mathematical modeling of cement paste microstructure by mosaic pattern: Part I. Formulation

1996 ◽  
Vol 11 (8) ◽  
pp. 1943-1952 ◽  
Author(s):  
Yunping Xi ◽  
Paul D. Tennis ◽  
Hamlin M. Jennings
Keyword(s):  
Cement Paste ◽  
Present Model ◽  
Spatial Arrangement ◽  
Structural Features ◽  
Evaluation Procedure ◽  
Model Parameters ◽  
Multiphase Microstructure ◽  
Water To Cement Ratio ◽  
The Relationship ◽  
Independent Parameters

This paper develops a mathematical model using mosaic patterns to characterize structural features of complex, multiphase, and multidimensional microstructures, such as those for cement paste. A multiphase microstructure can be characterized by m independent parameters; the first m– 1 parameters are equivalent to the volume fractions of the phases, while the final parameter describes the grain size, and thus, the spatial arrangement of the microstructure. An evaluation procedure for the parameters is given; they can be evaluated based on a 2D image, and then the 3D microstructure can be simulated by the present model. The relationship among the model parameters and material parameters, such as water-to-cement ratio and particle size distribution, are also established.

Formation of Microaggregates and organo-mineral composite building units: Novel pathways in the soil-parent rock continuum

2020 ◽  
Author(s):  
Kai Uwe Totsche
Keyword(s):  
Transition Zone ◽  
Solid Phase ◽  
Early Stage ◽  
Pore Space ◽  
Spatial Arrangement ◽  
Structural Features ◽  
Parent Rock ◽  
Permeable Media ◽  
Submicron Scale ◽  
Surface Alteration

<p><strong>Formation of Microaggregates and organo-mineral composite building units: Novel pathways in the soil-parent rock continuum</strong></p><p><strong> </strong></p><p><strong>Summary</strong></p><p> </p><p>Microaggregates and organo-mineral composite building seem to be unique structural features of natural permeable media like soils, rocks and aquifers. Thee develop in response to various aggregation processes and mechanisms that result in a non-random spatial arrangement of the solid phase already at the submicron scale. Soil microaggregates are defined as compound structures smaller <0.25mm, comprising the colloidal-sized and nanoparticulate composite building units and the organo-mineral composites (Totsche et al. 2018). Noteworthy, microaggregates, may be present as suspended or colloidally-dispersed components of the mobile phase. As such, they are prone to transport with the seepage and may affect the surface and pore-space properties. Surface alteration by interactions of seepage components with immobile surfaces is likely an important, yet essentially unexplored pathway triggering formation of microaggregates in the soil-parent rock continuum. In matured soils, the commonly found associations of clays with other, often poorly crystallized but highly reactive minerals and organic matter is the consequence of nucleation in the chemically heterogeneous soil suspension. Both pathways coexist and can be studied in the soil-parent-rock transition zone were weathering and formation/alteration of secondary mineral phases are still in the early stage<strong>. </strong>The stability of microaggregates and their interactions are dependent on wetting-drying and in turn by hydration-dehydration cycles. Such moisture-related dynamics regularly take place in soils of the temperate regions even down to the soil-parent-rock transition zone and suggests that the hydraulic and osmotic stress and their history results in attachment, detachment, translocation and accumulation. The presentation will We focus on two so far vastly ignored formation pathways of microaggregates and composite building units, i.e., the “geochemical inheritance” and “heteroaggregation from suspension”, thereby considering the role of dynamic relocation of composite building units and microaggregate forming materials from upstream compartments.</p><p> </p><p>Totsche K.U., Amelung W., Gerzabek M.H., Guggenberger G., Klumpp E., Knief C., Lehndorff E., Mikutta R., Peth S., Prechtel A., Ray N., Kögel-Knabner I. (2018) Microaggregates in soils. Journal of Plant Nutrition and Soil Science 181(1), 104-136.</p>

scholarly journals COMPARATIVE FEATURES OF STRUCTURE AND PROPERTIES OF BIOMARKERS OF NAPHTHALAN PETROLEUM

2020 ◽  
Vol 63 (7) ◽  
pp. 82-87
Author(s):  
Galina Yu. Kolchina ◽  
Eldar M. Movsumzade
Keyword(s):  
Biological Activity ◽  
Density Functional ◽  
Spatial Configuration ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Chair Conformation ◽  
Structural Features ◽  
The Body ◽  
Heavy Oils ◽  
Hydrogen Atoms

The results of studies of the structural features of the biomarkers of Naphthalan petroleum (in particular, R, S-cholestanes and hopanes with C28-C31) by the hybrid density functional in the approximation 6-311G+(d,p) are presented. It was shown that the studied substances have a quad-cyclopentanoperhydrophenanthrene system, which is inherent in resins and asphaltenes of heavy oils, and is also characterized by a three-dimensional spatial configuration. Compounds containing such a ring system are of great importance both for the body, including when exposed to antimicrobial reagents. The structure and position of the side groups and atoms adjacent to the main cycle, the position of double bonds in the molecule, and the spatial configuration have a definite effect on the biological activity of the biomarkers of Naphthalan petroleum. The calculated geometric parameters of the studied compounds show that the molecules are stable, and the stability is determined by the conformation of the rings (cyclohexane rings have the chair conformation, and cyclopentane rings have half-chairs), the nature of the connection between each other and the spatial arrangement of hydrogen atoms, radicals and functional groups. From the calculated values of the torsion angles of cholestanes and hopanes, it was shown that the junction of the A/B, B/C and C/D cycles is in the trans configuration (118.37° - 129.94°). The studied molecules possess a trans-articulation of the rings at the 5,10-, 8,9-, and 13,14-positions (in the case of 5-10 hopanes, also at the 17,18-position). The bonds in the molecules that form the rings are slightly distorted, and the rings themselves are not flat. A relationship was found between the biological activity of triterpenes and their values of ionization potentials and electron affinity. The studied biomarkers are similar in geometry and energy parameters to betulin derivatives and can exhibit biological activity.

scholarly journals Manipulating Enzymes Properties with DNA Nanostructures

Molecules ◽  
2019 ◽  
Vol 24 (20) ◽  
pp. 3694 ◽  
Author(s):  
Jaekel ◽  
Stegemann ◽  
Saccà
Keyword(s):  
Nucleic Acids ◽  
Dna Nanotechnology ◽  
Functional Materials ◽  
Spatial Arrangement ◽  
Structural Features ◽  
Kinetic Properties ◽  
Dna Oligomers ◽  
Artificial Dna ◽  
Initial Survey ◽  
Enzyme Molecules

Nucleic acids and proteins are two major classes of biopolymers in living systems. Whereas nucleic acids are characterized by robust molecular recognition properties, essential for the reliable storage and transmission of the genetic information, the variability of structures displayed by proteins and their adaptability to the environment make them ideal functional materials. One of the major goals of DNA nanotechnology—and indeed its initial motivation—is to bridge these two worlds in a rational fashion. Combining the predictable base-pairing rule of DNA with chemical conjugation strategies and modern protein engineering methods has enabled the realization of complex DNA-protein architectures with programmable structural features and intriguing functionalities. In this review, we will focus on a special class of biohybrid structures, characterized by one or many enzyme molecules linked to a DNA scaffold with nanometer-scale precision. After an initial survey of the most important methods for coupling DNA oligomers to proteins, we will report the strategies adopted until now for organizing these conjugates in a predictable spatial arrangement. The major focus of this review will be on the consequences of such manipulations on the binding and kinetic properties of single enzymes and enzyme complexes: an interesting aspect of artificial DNA-enzyme hybrids, often reported in the literature, however, not yet entirely understood and whose full comprehension may open the way to new opportunities in protein science.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

Structural organization of escherichia coli ribosomes as determined by immuno electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 166-167 ◽  
Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Ribosomal Subunit ◽  
Spatial Arrangement ◽  
Small Subunit ◽  
Antibody Binding ◽  
Immuno Electron Microscopy

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

Measurement and Reduction of Radiation Damage in Frozen Hydrated Crystalline Specimens

1978 ◽  
Vol 36 (3) ◽  
pp. 70-77 ◽  
Author(s):  
R.M. Glaeser ◽  
S.B. Hayward
Keyword(s):  
Diffraction Pattern ◽  
Structural Information ◽  
Structural Disorder ◽  
Structural Features ◽  
Biological Macromolecules ◽  
Diffraction Intensity ◽  
Object Structure ◽  
Specimen Material ◽  
Unit Cells ◽  
Identical Unit

Highly ordered or crystalline biological macromolecules become severely damaged and structurally disordered after a brief electron exposure. Evidence that damage and structural disorder are occurring is clearly given by the fading and eventual disappearance of the specimen's electron diffraction pattern. The fading and disappearance of sharp diffraction spots implies a corresponding disappearance of periodic structural features in the specimen. By the same token, there is a oneto- one correspondence between the disappearance of the crystalline diffraction pattern and the disappearance of reproducible structural information that can be observed in the images of identical unit cells of the object structure. The electron exposures that result in a significant decrease in the diffraction intensity will depend somewhat upon the resolution (Bragg spacing) involved, and can vary considerably with the chemical makeup and composition of the specimen material.

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