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Spin‐Labeled Heparins as Polarizing Agents for Dynamic Nuclear Polarization
Author(s) -
Dollmann Björn C.,
Kleschyov Andrei L.,
Sen Vasily,
Golubev Valery,
Schreiber Laura M.,
Spiess Hans W.,
Münnemann Kerstin,
Hinderberger Dariush
Publication year - 2010
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201000559
Subject(s) - electron paramagnetic resonance , chemistry , nuclear overhauser effect , hyperfine structure , nuclear magnetic resonance , spin polarization , macromolecule , radical , spin (aerodynamics) , polarization (electrochemistry) , hyperpolarization (physics) , relaxation (psychology) , nuclear magnetic resonance spectroscopy , chemical physics , electron , atomic physics , stereochemistry , physics , organic chemistry , psychology , social psychology , biochemistry , quantum mechanics , thermodynamics
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 1 H 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 ( T 1ne ). 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.