Spin‐Labeled Heparins as Polarizing Agents for Dynamic Nuclear Polarization |
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Authors: | Björn C. Dollmann Dr. Andrei L. Kleschyov Dr. Vasily Sen Dr. Valery Golubev Prof. Dr. Laura M. Schreiber Prof. Dr. Hans W. Spiess Dr. Kerstin Münnemann Dr. Dariush Hinderberger |
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Affiliation: | 1. Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany), Fax: (+49)?6131‐379‐100;2. Second Department of Medicine, Johannes Gutenberg University, Langenbeckstr. 1, 55131 Mainz (Germany);3. Institute of Problems of Chemical Physics, Russian Academy of Science, Acad. Semenov av. 1, 142431 Chernogolovka (Russia);4. Johannes Gutenberg University Medical Center, Langenbeckstr. 1, 55131 Mainz (Germany) |
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Abstract: | A potentially biocompatible class of spin‐labeled macromolecules, spin‐labeled (SL) heparins, and their use as nuclear magnetic resonance (NMR) signal enhancers are introduced. The signal enhancement is achieved through Overhauser‐type dynamic nuclear polarization (DNP). All presented SL‐heparins show high 1H DNP enhancement factors up to E=?110, which validates that effectively more than one hyperfine line can be saturated even for spin‐labeled polarizing agents. The parameters for the Overhauser‐type DNP are determined and discussed. A striking result is that for spin‐labeled heparins, the off‐resonant electron paramagnetic resonance (EPR) hyperfine lines contribute a non‐negligible part to the total saturation, even in the absence of Heisenberg spin exchange (HSE) and electron spin‐nuclear spin relaxation (T1ne). As a result, we conclude that one can optimize the use of, for example, biomacromolecules for DNP, for which only small sample amounts are available, by using heterogeneously distributed radicals attached to the molecule. |
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Keywords: | dynamic nuclear polarization EPR spectroscopy macromolecules NMR spectroscopy spin labels |
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