scholarly journals X-ray crystallographic studies of RoAb13 bound to PIYDIN, a part of the N-terminal domain of C-C chemokine receptor 5

IUCrJ ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 678-683
Author(s):  
Lata Govada ◽  
Emmanuel Saridakis ◽  
Sean C. Kassen ◽  
Ahmad Bin-Ramzi ◽  
Rhodri Marc Morgan ◽  
...  
Keyword(s):  
Antibody Response ◽  
Electron Density ◽  
Chemokine Receptor ◽  
Difference Electron Density ◽  
X Ray ◽  
Terminal Domain ◽  
Hiv Entry ◽  
Core Peptide ◽  
A Site ◽  
Chemokine Receptor 5

C-C chemokine receptor 5 (CCR5) is a major co-receptor molecule used by HIV-1 to enter cells. This led to the hypothesis that stimulating an antibody response would block HIV with minimal toxicity. Here, X-ray crystallographic studies of the anti-CCR5 antibody RoAb13 together with two peptides were undertaken: one peptide is a 31-residue peptide containing the PIYDIN sequence and the other is the PIDYIN peptide alone, where PIYDIN is part of the N-terminal region of CCR5 previously shown to be important for HIV entry. In the presence of the longer peptide (the complete N-terminal domain), difference electron density was observed at a site within a hypervariable CDR3 binding region. In the presence of the shorter core peptide PIYDIN, difference electron density is again observed at this CDR3 site, confirming consistent binding for both peptides. This may be useful in the design of a new biomimetic to stimulate an antibody response to CCR5 in order to block HIV infection.

Chemokine receptor-5 (CCR5) is a receptor for the HIV entry inhibitor peptide T (DAPTA)

2005 ◽  
Vol 67 (2) ◽  
pp. 83-92 ◽  
Author(s):  
Maria T. Polianova ◽  
Francis W. Ruscetti ◽  
Candace B. Pert ◽  
Michael R. Ruff
Keyword(s):  
Chemokine Receptor ◽  
Entry Inhibitor ◽  
Peptide T ◽  
Inhibitor Peptide ◽  
Hiv Entry ◽  
Chemokine Receptor 5

Synchrotron X-ray study of Er3Al5O12 and Yb3Al5O12 garnets

2001 ◽  
Vol 57 (2) ◽  
pp. 136-141 ◽  
Author(s):  
Barbara Etschmann ◽  
Victor Streltsov ◽  
Nobuo Ishizawa ◽  
E. N. Maslen
Keyword(s):  
Rare Earth ◽  
Electron Density ◽  
Relative Position ◽  
Nearest Neighbor ◽  
Difference Electron Density ◽  
X Ray ◽  
Density Maps ◽  
Structure Factors ◽  
The Difference ◽  
The Rare Earth

Structure factors for Er3Al5O12 and Yb3Al5O12 garnets were measured using focused synchrotron X-radiation, with λ = 0.7500 (2) and 0.7000 (2) Å, respectively. The difference electron density maps for Er3Al5O12 and Yb3Al5O12 were similar, as expected. This was attributed to the 4f electrons being shielded, which reduces their effectiveness in chemical bonding and the relative position of the rare-earth atoms in the periodic table. The symmetry of the difference electron density around the rare-earth atoms was found to reflect that of the cation geometry, emphasizing the importance of second nearest-neighbor interactions. This is consistent with the view that oxide-type structures may be regarded as a packed array of cations with anions in the interstices.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

Chemical and Electrochemical Heteroepitaxial Growth of Chalcogenide Semiconductors from Solutions

1996 ◽  
Vol 451 ◽  
Author(s):  
D. Lincot ◽  
M. J. Furlong ◽  
M. Froment ◽  
R. Cortes ◽  
M. C. Bernard
Keyword(s):  
Heteroepitaxial Growth ◽  
X Ray Diffraction ◽  
Basic Principles ◽  
Lattice Match ◽  
X Ray ◽  
Chalcogenide Semiconductors ◽  
Influence Of Temperature On ◽  
Deposition Processes ◽  
A Site ◽  
Site Selective

ABSTRACTChalcogenide semiconductors have been deposited epitaxially from aqueous solutions either chemically or electrochemically at growth rates of up to 0.7 μmhr−1. After recalling the basic principles of these deposition processes, results are presented concerning chemically deposited CdS on InP, GaP and CuInSe2 substrates, electrodeposited CdTe on InP, and CdSAnP heterostructures. Characterisation of these structures by RHEED, TEM, HRTEM, and glazing angle X ray diffraction allows to analyse the effects of substrate orientation, polarity, lattice match plus the influence of temperature on epitaxial growth. These results are discussed in terms of self organisation and a site selective growth mechanisms due to the free enegy of formation of each compound.

Elucidating the Disparate Inhibitory Mechanisms of Novel 1-Heteroaryl1,3-Propanediamine Derivatives and Maraviroc towards C-C Chemokine Receptor 5: Insights for Structural Modifications in HIV-1 Drug Discovery

2020 ◽  
Vol 17 ◽  
Author(s):  
Patrick Appiah-Kubi ◽  
Fisayo Andrew Olotu ◽  
Mahmoud E. S. Soliman
Keyword(s):  
Drug Discovery ◽  
Chemokine Receptor ◽  
Competitive Inhibition ◽  
Dynamic Effect ◽  
Triazole Ring ◽  
Internal Dynamic ◽  
V3 Loop ◽  
Structural Modifications ◽  
Hiv 1 ◽  
Chemokine Receptor 5

Introduction: Blocking Human Immunodeficiency Virus type 1 (HIV-1) entry via C-C chemokine receptor 5 (CCR5) inhibition has remained an essential strategy in HIV drug discovery. This underlies the development of CCR5 blockers, such as Maraviroc, which, however, elicits undesirable side effects despite its potency. Background: Recent lead optimization efforts led to the discovery of novel 1-heteroaryl-1,3-propanediamine derivatives; Compd-21 and -34, which were ~3 times more potent than Maraviroc, with improved pharmacokinetics. However, atomistic molecular interaction mechanism of how slight structural variance between these inhibitors significantly affects their binding profiles have not been elucidated. Method: This study employed explicit lipid bilayer molecular dynamics (MD) simulations, and advance analyses to explore these inhibitory discrepancies. Results: Findings revealed that the thiophene moiety substitution common to Compd-21 and -34 enhanced their CCR5- inhibitory activities due to complementary high-affinity interactions with Trp862.60, Tyr1083.32, Tyr2516.51, Glu2837.39. These cumulatively accounted for their ΔGbind which were higher than Maraviroc. Binding dynamics further revealed that the compounds mediated direct competitive inhibition at CCR5 by blocking the gp120 V3 loop. Furthermore, constituent tropane and triazole moieties in the compounds commonly engaged in interactions with Glu2837.39 and Trp862.60, respectively. Structural analyses also revealed that both Compd-21 and -34 elicited distinct internal dynamic effect on CCR5 relative to Maraviroc. Conclusion: Structural modifications at the thiophene substituent and the addition of new functional groups to the triazole ring may enhance inhibitor competition with gp120 V3-loop. Findings herein highlighted would contribute to future structure-based design of inhibitors of HIV-1 CCR5 with improved potencies.

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