TY - JOUR
T1 - Overhauser dynamic nuclear polarization and molecular dynamics simulations using pyrroline and piperidine ring nitroxide radicals
AU - Armstrong, Brandon D.
AU - Soto, Patricia
AU - Shea, Joan Emma
AU - Han, Songi
N1 - Funding Information:
We thank Prof. Siegfried Stapf and Dr. Carlos Mattea at the Technical University of Illmenau for performing the field cycling relaxometry measurements reported here. We thank Evan McCarney for helpful discussions. Computer support was provided by the Lonestar cluster at the Texas Advanced Computing Center (LRAC MCA 05S027). This work was partially supported by the MRL program of the National Science Foundation under Grant No. DMR05-20415, the Faculty Early Career Award (Grant CHE-0645536), the W.M. Keck Award for Science and Engineering, the David and Lucile Packard Foundation, and NSF Grant MCB 0642086.
PY - 2009/9
Y1 - 2009/9
N2 - The efficiency of Overhauser dynamic nuclear polarization (DNP) depends on the local dynamics modulating the dipolar coupling between the two interacting spins. By attaching nitroxide based spin labels to molecules and by measuring the 1H DNP response of solvent water, information about the local hydration dynamics near the spin label can be obtained. However, there are two commonly used types of nitroxide ring structures; a pyrroline based and a piperidine based molecule. It is important to know when comparing different experiments, whether changes in DNP enhancements are due to changes in local hydration dynamics or because of the different spin label structures. In this study we investigate the key parameters affecting DNP signal enhancements for 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-oxyl, a 5-membered ring nitroxide radical, and for 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy, a 6-membered ring nitroxide radical. Using X-Band DNP, field cycling relaxometry, and molecular dynamics simulations, we conclude that the key parameters affecting the DNP amplitude of the 1H signal of water to be equal when using either nitroxide. Thus, experiments measuring hydration dynamics using either type of spin labels may be compared.
AB - The efficiency of Overhauser dynamic nuclear polarization (DNP) depends on the local dynamics modulating the dipolar coupling between the two interacting spins. By attaching nitroxide based spin labels to molecules and by measuring the 1H DNP response of solvent water, information about the local hydration dynamics near the spin label can be obtained. However, there are two commonly used types of nitroxide ring structures; a pyrroline based and a piperidine based molecule. It is important to know when comparing different experiments, whether changes in DNP enhancements are due to changes in local hydration dynamics or because of the different spin label structures. In this study we investigate the key parameters affecting DNP signal enhancements for 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-oxyl, a 5-membered ring nitroxide radical, and for 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy, a 6-membered ring nitroxide radical. Using X-Band DNP, field cycling relaxometry, and molecular dynamics simulations, we conclude that the key parameters affecting the DNP amplitude of the 1H signal of water to be equal when using either nitroxide. Thus, experiments measuring hydration dynamics using either type of spin labels may be compared.
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U2 - 10.1016/j.jmr.2009.05.013
DO - 10.1016/j.jmr.2009.05.013
M3 - Article
C2 - 19535275
AN - SCOPUS:68049105109
VL - 200
SP - 137
EP - 141
JO - Journal of Magnetic Resonance
JF - Journal of Magnetic Resonance
SN - 1090-7807
IS - 1
ER -