title: Heteronuclear Cross-Relaxation under Solid-State Dynamic Nuclear Polarization.
abstract: We report on the spontaneous polarization transfer from dynamically hyperpolarized1H to13C during magic-angle spinning dynamic nuclear polarization (DNP) at temperatures around 100 K. The transfer is mediated by1H-13C cross-relaxation within methyl groups due to reorientation dynamics, and results in an inverted13C NMR signal of enhanced amplitude. Further spreading of transferred polarization can then occur via13C-13C spin-diffusion. The resulting process is equal to the nuclear Overhauser effect (NOE) where typically continuous saturation of1H by radio frequency irradiation is employed. Here, hyperpolarization by irradiation with microwaves in the presence of typical bis-nitroxide polarizing agents is utilized for steady-state displacement of1H polarization from thermal equilibrium and perpetual spin-lattice relaxation. An effective13C enhancement factor of up to -15 has been measured. Presence of Gd(III) furthermore amplifies the effect likely by accelerated relaxation of1H. We provide experimental evidence for the proposed mechanism and show that DNP-induced cross-relaxation is a robust feature within proteins and single amino acids and discuss potential applications.
authors.affiliation: Institute of Physical and Theoretical Chemistry and Institute of Biophysical Chemistry, Goethe University Frankfurt , Max-von-Laue-Str. 7-9, 60438 Frankfurt am Main, Germany.|Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt , Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany.
authors.forename: Diane
authors.initials: D
authors.lastname: Daube
authors.affiliation: Institute of Physical and Theoretical Chemistry and Institute of Biophysical Chemistry, Goethe University Frankfurt , Max-von-Laue-Str. 7-9, 60438 Frankfurt am Main, Germany.|Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt , Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany.
authors.forename: Victoria
authors.initials: V
authors.lastname: Aladin
authors.affiliation: Institute of Physical and Theoretical Chemistry and Institute of Biophysical Chemistry, Goethe University Frankfurt , Max-von-Laue-Str. 7-9, 60438 Frankfurt am Main, Germany.|Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt , Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Heiliger
authors.affiliation: Institute of Physical and Theoretical Chemistry and Institute of Biophysical Chemistry, Goethe University Frankfurt , Max-von-Laue-Str. 7-9, 60438 Frankfurt am Main, Germany.|Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt , Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany.
authors.forename: Johannes J
authors.initials: JJ
authors.lastname: Wittmann
authors.affiliation: Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt , Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany.|Institute of Organic Chemistry and Chemical Biology, Goethe University Frankfurt , Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany.
authors.forename: Dominic
authors.initials: D
authors.lastname: Barthelmes
authors.affiliation: Institute of Physical and Theoretical Chemistry and Institute of Biophysical Chemistry, Goethe University Frankfurt , Max-von-Laue-Str. 7-9, 60438 Frankfurt am Main, Germany.|Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt , Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Bengs
authors.affiliation: Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt , Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany.|Institute of Organic Chemistry and Chemical Biology, Goethe University Frankfurt , Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Schwalbe
authors.affiliation: Institute of Physical and Theoretical Chemistry and Institute of Biophysical Chemistry, Goethe University Frankfurt , Max-von-Laue-Str. 7-9, 60438 Frankfurt am Main, Germany.|Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt , Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany.
authors.forename: Björn
authors.identifier: 0000-0003-3937-9137
authors.initials: B
authors.lastname: Corzilius