Assessing The Functional Structure Of Molecular Transporters By Epr Spectroscopy


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Assessing the Functional Structure of Molecular Transporters by EPR Spectroscopy


Assessing the Functional Structure of Molecular Transporters by EPR Spectroscopy

Author: Matthias J.N.Junk

language: en

Publisher: Springer Science & Business Media

Release Date: 2012-01-05


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In his thesis, Matthias Junk takes an innovative approach to assess the local structure and dynamics of biological and synthetic amphiphilic macromolecules capable of transporting small molecules. Replacing the latter with stable radicals, he uses state-of-the-art electron paramagnetic resonance (EPR) spectroscopy to describe the highly relevant transport function from the viewpoint of the guest molecules. Such, he demonstrates that the functional structure of human serum albumin in solution significantly differs from its crystal structure – a consequence of the protein’s adaptability to host various endogenous compounds and drug molecules. Further, he shows that the thermal collapse of thermoresponsive hydrogels and dendronized polymers leads to static and dynamic heterogeneities on the nanoscale. These heterogeneities bear consequences for the material’s hosting properties and enable unforeseen complex catalytic functionalities.

Assessing the Functional Structure of Molecular Transporters by EPR Spectroscopy


Assessing the Functional Structure of Molecular Transporters by EPR Spectroscopy

Author:

language: en

Publisher:

Release Date: 2010


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In this thesis, the self-assembled functional structure of a broad range of amphiphilic molecular transporters is studied. By employing paramagnetic probe molecules and ions, continuous-wave and pulse electron paramagnetic resonance spectroscopy reveal information about the local structure of these materials from the perspective of incorporated guest molecules. First, the transport function of human serum albumin for fatty acids is in the focus. As suggested by the crystal structure, the anchor points for the fatty acids are distributed asymmetrically in the protein. In contrast to the crystallographic findings, a remarkably symmetric entry point distribution of the fatty acid binding channels is found, which may facilitate the uptake and release of the guest molecules. Further, the metal binding of 1,2,3-triazole modified star-shaped cholic acid oligomers is studied. These biomimetic molecules are able to include and transport molecules in solvents of different polarity. A pre-arrangement of the triazole groups induces a strong chelate-like binding and close contact between guest molecule and metal ion. In absence of a preordering, each triazole moiety acts as a single entity and the binding affinity for metal ions is strongly decreased. Hydrogels based on N-isopropylacrylamide phase separate from water above a certain temperature. The macroscopic thermal collapse of these hydrogels is utilized as a tool for dynamic nuclear polarization. It is shown that a radical-free hyperpolarized solution can be achieved with a spin-labeled gel as separable matrix. On the nanoscale, these hydrogels form static heterogeneities in both structure and function. Collapsed regions protect the spin probes from a chemical decay while open, water-swollen regions act as catalytic centers. Similarly, thermoresponsive dendronized polymers form structural heterogeneities, which are, however, highly dynamic. At the critical temperature, they trigger the aggregation of the polymer into mesogl.

Electron Paramagnetic Resonance Spectroscopy


Electron Paramagnetic Resonance Spectroscopy

Author: Patrick Bertrand

language: en

Publisher: Springer Nature

Release Date: 2020-02-03


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This book shows how the fundamentals of electron paramagnetic resonance (EPR) spectroscopy are practically implemented and illustrates the diversity of current applications. The technique is used at various levels, and applications are presented in order of increasing difficulty, with reference to theoretically obtained results. This book features a diverse array of application examples, from fields such as ionizing radiation dosimetry, neurodegenerative diseases, structural transitions in proteins, and the origins of terrestrial life. The final chapter of this book highlights the principles and applications of the technique of ferromagnetic resonance spectroscopy, followed by a brief introduction to advanced EPR techniques such as electron spin echo envelope modulation (ESEEM), hyperfine sub-level correlation (HYSCORE), pulsed electron-electron double resonance (PELDOR), and continuous wave electron nuclear double resonance (ENDOR) experiments.