PGSE NMR Studies on DAB-Organo-Rhodium Dendrimers:  Evaluation of the Molecular Size, Self-Aggregation Tendency, and Surface Metal Density

2006 ◽  
Vol 25 (9) ◽  
pp. 2201-2208 ◽  
Author(s):  
Daniele Zuccaccia ◽  
Luigi Busetto ◽  
M. Cristina Cassani ◽  
Alceo Macchioni ◽  
Rita Mazzoni
Keyword(s):  
Molecular Size ◽  
Nmr Studies ◽  
Surface Metal ◽  
Pgse Nmr ◽  
Aggregation Tendency ◽  
Self Aggregation

scholarly journals The Palladium(II) Complex of Aβ4−16 as Suitable Model for Structural Studies of Biorelevant Copper(II) Complexes of N-Truncated Beta-Amyloids

2020 ◽  
Vol 21 (23) ◽  
pp. 9200
Author(s):  
Mariusz Mital ◽  
Kosma Szutkowski ◽  
Karolina Bossak-Ahmad ◽  
Piotr Skrobecki ◽  
Simon C. Drew ◽  
...  
Keyword(s):  
Supramolecular Assembly ◽  
Ros Generation ◽  
Suitable Model ◽  
Nmr Studies ◽  
Exchange Processes ◽  
Square Planar ◽  
Synthetic Procedure ◽  
Complex Forms ◽  
Pgse Nmr ◽  
Kinetic Trapping

The Aβ4−42 peptide is a major beta-amyloid species in the human brain, forming toxic aggregates related to Alzheimer’s Disease. It also strongly chelates Cu(II) at the N-terminal Phe-Arg-His ATCUN motif, as demonstrated in Aβ4−16 and Aβ4−9 model peptides. The resulting complex resists ROS generation and exchange processes and may help protect synapses from copper-related oxidative damage. Structural characterization of Cu(II)Aβ4−x complexes by NMR would help elucidate their biological function, but is precluded by Cu(II) paramagneticism. Instead we used an isostructural diamagnetic Pd(II)-Aβ4−16 complex as a model. To avoid a kinetic trapping of Pd(II) in an inappropriate transient structure, we designed an appropriate pH-dependent synthetic procedure for ATCUN Pd(II)Aβ4−16, controlled by CD, fluorescence and ESI-MS. Its assignments and structure at pH 6.5 were obtained by TOCSY, NOESY, ROESY, 1H-13C HSQC and 1H-15N HSQC NMR experiments, for natural abundance 13C and 15N isotopes, aided by corresponding experiments for Pd(II)-Phe-Arg-His. The square-planar Pd(II)-ATCUN coordination was confirmed, with the rest of the peptide mostly unstructured. The diffusion rates of Aβ4−16, Pd(II)-Aβ4−16 and their mixture determined using PGSE-NMR experiment suggested that the Pd(II) complex forms a supramolecular assembly with the apopeptide. These results confirm that Pd(II) substitution enables NMR studies of structural aspects of Cu(II)-Aβ complexes.

Self-Aggregation Tendency of All Species Involved in the Catalytic Cycle of Bifunctional Transfer Hydrogenation

2009 ◽  
Vol 28 (4) ◽  
pp. 960-967 ◽  
Author(s):  
Gianluca Ciancaleoni ◽  
Cristiano Zuccaccia ◽  
Daniele Zuccaccia ◽  
Eric Clot ◽  
Alceo Macchioni
Keyword(s):  
Catalytic Cycle ◽  
Transfer Hydrogenation ◽  
Aggregation Tendency ◽  
Self Aggregation

PGSE NMR Studies on RAPTA Derivatives: Evidence for the Formation of H-Bonded Dicationic Species

2008 ◽  
Vol 27 (7) ◽  
pp. 1649-1652 ◽  
Author(s):  
Sandra Bolaño ◽  
Gianluca Ciancaleoni ◽  
Jorge Bravo ◽  
Luca Gonsalvi ◽  
Alceo Macchioni ◽  
...  
Keyword(s):  
Nmr Studies ◽  
Pgse Nmr

Transport heterogeneity in porous pellets—I. PGSE NMR studies

1995 ◽  
Vol 50 (2) ◽  
pp. 309-326 ◽  
Author(s):  
Michael P. Hollewand ◽  
Lynn F. Gladden
Keyword(s):  
Nmr Studies ◽  
Pgse Nmr

Self-Aggregation Tendency of Zirconocenium Ion Pairs Which Model Polymer-Chain-Carrying Species in Aromatic and Aliphatic Solvents with Low Polarity

2008 ◽  
Vol 14 (22) ◽  
pp. 6589-6592 ◽  
Author(s):  
Luca Rocchigiani ◽  
Cristiano Zuccaccia ◽  
Daniele Zuccaccia ◽  
Alceo Macchioni
Keyword(s):  
Polymer Chain ◽  
Ion Pairs ◽  
Aggregation Tendency ◽  
Self Aggregation

NMR Studies of Nanoscale Organization and Dynamics in Polymer Electrolytes

2004 ◽  
Vol 57 (12) ◽  
pp. 1185 ◽  
Author(s):  
William S. Price ◽  
Yuichi Aihara ◽  
Kikuko Hayamizu
Keyword(s):  
Molecular Weight ◽  
Spin Echo ◽  
Three Dimensional ◽  
Nmr Relaxation ◽  
Polymer Chains ◽  
Porous Polymer ◽  
Random Copolymers ◽  
Nmr Studies ◽  
Viscous Liquids ◽  
Pgse Nmr

Multinuclear (i.e., 7Li, 19F, and 1H) NMR relaxation and pulsed field gradient spin-echo (PGSE) NMR translational diffusion measurements have been used to study the reorientational and translational dynamics of the polymeric, anionic, and cationic species in a polymer electrolyte system composed of high-molecular-weight comb-branched polyethers and their precursor macromonomers of cross-linked random copolymers, with and without LiN(SO2CF3)2 (LiTFSI) doping. The macromonomers are derivatives of glycerol bonded to ethylene oxide-co-propylene oxide (m(EO-PO)) and are viscous liquids with a molecular weight of approximately 8000. The results were consistent with a picture of the lithium ions undergoing local motions near the polymer chains, whereas the anions diffuse through a slowly fluctuating three-dimensional porous polymer matrix. Four years later, the macromonomer electrolyte samples were re-measured to investigate the effects of long-term aging. The NMR data revealed that the electrolyte has undergone significant structural relaxation. The findings shed light on the evolving molecular architectures that influence conductivity and help to explain the non-ideal conductivity behaviour.

scholarly journals Inhibition of fibril formation in β-amyloid peptide by a novel series of benzofurans

1999 ◽  
Vol 340 (1) ◽  
pp. 283-289 ◽  
Author(s):  
David R. HOWLETT ◽  
Amanda E. PERRY ◽  
Fiona GODFREY ◽  
Jane E. SWATTON ◽  
Kevin H. JENNINGS ◽  
...  
Keyword(s):  
Binding Assay ◽  
Close Correlation ◽  
Fibril Formation ◽  
Biologically Active ◽  
Amyloid Peptide ◽  
Binding Assays ◽  
Nmr Studies ◽  
Β Amyloid ◽  
Β Amyloid Peptide ◽  
Self Aggregation

A series of benzofuran derivatives have been identified as inhibitors of fibril formation in the β-amyloid peptide. The activity of these compounds has been assessed by a novel fibril-formation-specific immunoassay and for their effects on the production of a biologically active fibril product. The inhibition afforded by the compounds seems to be associated with their binding to β-amyloid, as identified by scintillation proximity binding assay. Binding assays and NMR studies also indicate that the inhibition is associated with self-aggregation of the compounds. There is a close correlation between the activity of the benzofurans as inhibitors of fibril formation and their ability to bind to β-amyloid. Non-benzofuran inhibitors of the fibril formation process do not seem to bind to the same site on the β-amyloid molecule as the benzofurans. Thus a specific recognition site might exist for benzofurans on β-amyloid, binding to which seems to interfere with the ability of the peptide to form fibrils.

Light Scattering and NMR Studies on the Self-Aggregation of Sodiumn-Hexyl Sulfate in Aqueous Electrolyte Solution

Langmuir ◽  
2000 ◽  
Vol 16 (4) ◽  
pp. 1620-1625 ◽  
Author(s):  
Juan M. Ruso ◽  
David Attwood ◽  
Pablo Taboada ◽  
Víctor Mosquera ◽  
Félix Sarmiento
Keyword(s):  
Light Scattering ◽  
Electrolyte Solution ◽  
Aqueous Electrolyte ◽  
The Self ◽  
Aqueous Electrolyte Solution ◽  
Nmr Studies ◽  
Self Aggregation
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