Structure and conformation of the hydrate of 8,11-dihydroxypentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-carbolactam

1996 ◽  
Vol 52 (5) ◽  
pp. 838-841 ◽  
Author(s):  
H. G. Kruger ◽  
F. J. C. Martins ◽  
A. M. Viljoen ◽  
J. C. A. Boeyens ◽  
L. M. Cook ◽  
...  
Keyword(s):  
Random Distribution ◽  
Crystallographic Analysis ◽  
Crystalline Modification ◽  
Functional Region ◽  
Cage Compound ◽  
Molecular Arrangement ◽  
Water Of Hydration ◽  
Hydrated Crystal ◽  
Network Of Hydrogen Bonds ◽  
Bond Network

The crystalline modification of the title compound from aqueous medium depends critically on factors such as concentration and pH. Crystallographic analysis of a hydrated crystal showed that this effect related to the formation of an extended network of hydrogen bonds that requires the water molecule, as H2O, to be hydrogen bonded three ways. The crystals are monoclinic, C2/c, a = 10.030 (1), b = 9.840 (2), c = 21.625 (2) Å, β = 90.87 (1)°, Z = 8. The hydrogen-bond network between water of hydration and the functional groups on the cage compound has identical geometries for both chiralities and during crystallization there is hence no discrimination between enantiomers. Both forms are thus accommodated at the same sites in random distribution, causing disorder of the molecular fragment remote from the functional region. The final arrangement is similar to a hydrated solid solution of the two enantiomers with an IR spectrum sufficiently different from the anhydrous form to suggest a different molecular arrangement.

Structural and thermodynamic analyses of interactions between death-associated protein kinase 1 and anthraquinones

2020 ◽  
Vol 76 (5) ◽  
pp. 438-446 ◽  
Author(s):  
Takeshi Yokoyama ◽  
Peter Wijaya ◽  
Yuto Kosaka ◽  
Mineyuki Mizuguchi
Keyword(s):  
Protein Kinase ◽  
Amyloid Β ◽  
Crystallographic Analysis ◽  
Binding Affinities ◽  
Hydrogen Bond Network ◽  
Lead Compound ◽  
Death Associated Protein Kinase ◽  
Bond Network ◽  
Inhibition Potencies ◽  
Potent Inhibitory Activity

Death-associated protein kinase 1 (DAPK1) is a serine/threonine protein kinase that regulates apoptosis and autophagy. DAPK1 is considered to be a therapeutic target for amyloid-β deposition, endometrial adenocarcinomas and acute ischemic stroke. Here, the potent inhibitory activity of the natural anthraquinone purpurin against DAPK1 phosphorylation is shown. Thermodynamic analysis revealed that while the binding affinity of purpurin is similar to that of CPR005231, which is a DAPK1 inhibitor with an imidazopyridazine moiety, the binding of purpurin was more enthalpically favorable. In addition, the inhibition potencies were correlated with the enthalpic changes but not with the binding affinities. Crystallographic analysis of the DAPK1–purpurin complex revealed that the formation of a hydrogen-bond network is likely to contribute to the favorable enthalpic changes and that stabilization of the glycine-rich loop may cause less favorable entropic changes. The present findings indicate that purpurin may be a good lead compound for the discovery of inhibitors of DAPK1, and the observation of enthalpic changes could provide important clues for drug development.

scholarly journals Neutron Crystallographic Analysis Elucidates the Hydrogen-Bond Network and pH Sensitivity of Human Transthyretin

2014 ◽  
Vol 56 (2) ◽  
pp. 129-132
Author(s):  
Takeshi YOKOYAMA ◽  
Mineyuki MIZUGUCHI ◽  
Katsuhiro KUSAKA ◽  
Ichiro TANAKA ◽  
Nobuo NIIMURA
Keyword(s):  
Hydrogen Bond ◽  
Crystallographic Analysis ◽  
Ph Sensitivity ◽  
Hydrogen Bond Network ◽  
Bond Network

Random isn't real: How the patchy distribution of ecological rewards may generate “incentive hope”

2019 ◽  
Vol 42 ◽  
Author(s):  
Laurel Symes ◽  
Thalia Wheatley
Keyword(s):  
Natural Environment ◽  
Random Distribution ◽  
Spatiotemporal Distribution ◽  
Patchy Distribution ◽  
Distribution Of Resources

AbstractAnselme & Güntürkün generate exciting new insights by integrating two disparate fields to explain why uncertain rewards produce strong motivational effects. Their conclusions are developed in a framework that assumes a random distribution of resources, uncommon in the natural environment. We argue that, by considering a realistically clumped spatiotemporal distribution of resources, their conclusions will be stronger and more complete.

Quaternary structure of Limulus polyphemus hemocyanin

1978 ◽  
Vol 36 (2) ◽  
pp. 176-177
Author(s):  
T. Wichertjes ◽  
E.J. Kwak ◽  
E.F.J. Van Bruggen
Keyword(s):  
Electron Microscopy ◽  
Functional Properties ◽  
Horseshoe Crab ◽  
Temperature Jump ◽  
Quaternary Structure ◽  
Crystallographic Analysis ◽  
Limulus Polyphemus ◽  
Oxygen Binding ◽  
X Ray ◽  
Intact Molecule

Hemocyanin of the horseshoe crab (Limulus polyphemus) has been studied in nany ways. Recently the structure, dissociation and reassembly was studied using electron microscopy of negatively stained specimens as the method of investigation. Crystallization of the protein proved to be possible and X-ray crystallographic analysis was started. Also fluorescence properties of the hemocyanin after dialysis against Tris-glycine buffer + 0.01 M EDTA pH 8.9 (so called “stripped” hemocyanin) and its fractions II and V were studied, as well as functional properties of the fractions by NMR. Finally the temperature-jump method was used for assaying the oxygen binding of the dissociating molecule and of preparations of isolated subunits. Nevertheless very little is known about the structure of the intact molecule. Schutter et al. suggested that the molecule possibly consists of two halves, combined in a staggered way, the halves themselves consisting of four subunits arranged in a square.

Decoration of specific sites on freeze-fractured membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 140-141
Author(s):  
H. Gross ◽  
H. Moor
Keyword(s):  
Pure Water ◽  
Freeze Fracture ◽  
Chemical Properties ◽  
Surface Forces ◽  
Sulfate Pentahydrate ◽  
Copper Sulfate Pentahydrate ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
Small Container ◽  
Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

Organisation in the Structure of the Cytoplasmic Ground Substance

1978 ◽  
Vol 36 (3) ◽  
pp. 627-639
Author(s):  
K.R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Random Distribution ◽  
Ground Substance ◽  
The Matrix ◽  
Cell Processes ◽  
Cytoplasmic Ground Substance

Most types of cells are known from their structure and overall form to possess a characteristic organization. In some instances this is evident in the non-random disposition of organelles and such system subunits as cisternae of the endoplasmic reticulum or the Golgi complex. In others it appears in the distribution and orientation of cytoplasmic fibrils. And in yet others the organization finds expression in the non-random distribution and orientation of microtubules, especially as found in highly anisometric cells and cell processes. The impression is unavoidable that in none of these cases is the organization achieved without the involvement of the cytoplasmic ground substance (CGS) or matrix. This impression is based on the fact that a matrix is present and that in all instances these formed structures, whether membranelimited or filamentous, are suspended in it. In some well-known instances, as in arrays of microtubules which make up axonemes and axostyles, the matrix resolves itself into bridges (and spokes) between the microtubules, bridges which are in some cases very regularly disposed and uniform in size (Mcintosh, 1973; Bloodgood and Miller, 1974; Warner and Satir, 1974).

Some Observations on Intra-Mitochondrial Crystals

1977 ◽  
Vol 35 ◽  
pp. 406-407
Author(s):  
J. A. Clarke ◽  
D. N. Landon ◽  
P. R. Ward
Keyword(s):  
Cytochrome B ◽  
Mitochondrial Myopathy ◽  
Crystallographic Analysis ◽  
Mitochondrial Membranes ◽  
Electron Microscopes ◽  
Muscle Biopsies

Intra-mitochondrial crystals have been noted in muscle biopsies from patients in a wide variety of diseased states. As far as we are aware, none of these crystals have been subjected to detailed crystallographic analysis. Recently, similar crystals were observed in a biopsy from a patient with a mitochondrial myopathy, characterised by a deficiency in reducible cytochrome b (Morgan-Hughes, J. A., Darveniza, P., Kahn, S. N., Landon, D. N., Sherratt, R. M., Land, J. M. and Clark, J. B., 1977, Brain, In Press). Aldehyde-fixed, osmicated resin imbedded material was examined using Siemens, JEOL and Phillips electron microscopes with goniometer specimen stages. The crystals generally lay between the outer and inner mitochondrial membranes and measured 1 - 3 μm in length and 0.1 - 0.3 μm in width. Characteristically, these crystals revealed specific periodicities.

Electron microscopy of rabbit FC crystals

1983 ◽  
Vol 41 ◽  
pp. 730-731
Author(s):  
Robert A. Grant ◽  
Laura L. Degn ◽  
Wah Chiu ◽  
John Robinson
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Molecular Replacement ◽  
X Ray ◽  
X Ray Crystallography ◽  
Resolution Electron ◽  
Replacement Technique ◽  
Hydrated Crystal ◽  
Molecular Structure Analysis

Proteolytic digestion of the immunoglobulin IgG with papain cleaves the molecule into an antigen binding fragment, Fab, and a compliment binding fragment, Fc. Structures of intact immunoglobulin, Fab and Fc from various sources have been solved by X-ray crystallography. Rabbit Fc can be crystallized as thin platelets suitable for high resolution electron microscopy. The structure of rabbit Fc can be expected to be similar to the known structure of human Fc, making it an ideal specimen for comparing the X-ray and electron crystallographic techniques and for the application of the molecular replacement technique to electron crystallography. Thin protein crystals embedded in ice diffract to high resolution. A low resolution image of a frozen, hydrated crystal can be expected to have a better contrast than a glucose embedded crystal due to the larger density difference between protein and ice compared to protein and glucose. For these reasons we are using an ice embedding technique to prepare the rabbit Fc crystals for molecular structure analysis by electron microscopy.

Glycogen in guinea pig neutrophils: Ultrastructural study of neutrophils at the intradermal site of BCG injection

1983 ◽  
Vol 41 ◽  
pp. 726-727
Author(s):  
Corazon D. Bucana
Keyword(s):  
Bone Marrow ◽  
Guinea Pig ◽  
Electron Density ◽  
Peritoneal Cavity ◽  
Ultrastructural Study ◽  
Guinea Pigs ◽  
Random Distribution ◽  
Glycogen Content ◽  
Polymorphonuclear Neutrophils ◽  
Ultrastructural Studies

In the circulating blood of man and guinea pigs, glycogen occurs primarily in polymorphonuclear neutrophils and platelets. The amount of glycogen in neutrophils increases with time after the cells leave the bone marrow, and the distribution of glycogen in neutrophils changes from an apparently random distribution to large clumps when these cells move out of the circulation to the site of inflammation in the peritoneal cavity. The objective of this study was to further investigate changes in glycogen content and distribution in neutrophils. I chose an intradermal site because it allows study of neutrophils at various stages of extravasation.Initially, osmium ferrocyanide and osmium ferricyanide were used to fix glycogen in the neutrophils for ultrastructural studies. My findings confirmed previous reports that showed that glycogen is well preserved by both these fixatives and that osmium ferricyanide protects glycogen from solubilization by uranyl acetate.I found that osmium ferrocyanide similarly protected glycogen. My studies showed, however, that the electron density of mitochondria and other cytoplasmic organelles was lower in samples fixed with osmium ferrocyanide than in samples fixed with osmium ferricyanide.

Morphology of Σ3{/70.53°} grain boundaries in a C15 intermetallic compound

1994 ◽  
Vol 52 ◽  
pp. 684-685
Author(s):  
Fuming Chu ◽  
D. P. Pope ◽  
D. S. Zhou ◽  
T. E. Mitchell
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Crystallographic Analysis ◽  
Laves Phase ◽  
Second Phase ◽  
Bright Field Image ◽  
Boundary Edge ◽  
Arc Melting ◽  
Fcc Lattice ◽  
Diffraction Patterns

A C15 Laves phase, HfV2+Nb, shows promising mechanical properties and here we describe the structure of its grain boundaries. The C15 Laves phase has a fcc lattice with a=7.4Å. An alloy of composition Hf14V64Nb22 (including a C15 matrix and a second phase of V-rich bcc solution) was made by arc-melting. The alloy was homogenized at 1200°C for 120h. Preliminary study concentrated on Σ3{<110>/70.53°} grain boundaries in the C15 phase using Philips 400T and CM 30 microscopes.The most-commonly observed morphology of Σ3{<110>/70.53°} grain boundaries in the C15 phase is a faceted boundary. A bright field image (BFI) of the faceted boundary and the corresponding diffraction patterns with the grain boundary edge-on are shown in Fig. 1(a). From the diffraction patterns using a <110> zone axis for both grains, it is obvious that this is a Σ3{<110>/70.53°} grain boundary. Crystallographic analysis shows that the Σ3{<110>/70.53°} grain boundaries selectively facet with the following relationships between the two grains: {111}1//{111}2, {112}1//{112}2, {111}1//{115}2, and {001}1//{221}2.

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