Cryogenic sample exchange NMR probe for magic angle spinning dynamic nuclear polarization
Author(s)Barnes, Alexander; Mak-Jurkauskas, Melody L.; Matsuki, Yoh; Bajaj, Vikram S.; van der Wel, Patrick C.A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Lugtenburg, Johan; Herzfeld, Judith; DeRocher, Ronald C.; Bryant, Jeffrey A.; Griffin, Robert Guy; ... Show more Show less
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We describe a cryogenic sample exchange system that dramatically improves the efficiency of magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments by reducing the time required to change samples and by improving long-term instrument stability. Changing samples in conventional cryogenic MAS DNP/NMR experiments involves warming the probe to room temperature, detaching all cryogenic, RF, and microwave connections, removing the probe from the magnet, replacing the sample, and reversing all the previous steps, with the entire cycle requiring a few hours. The sample exchange system described here—which relies on an eject pipe attached to the front of the MAS stator and a vacuum jacketed dewar with a bellowed hole—circumvents these procedures. To demonstrate the excellent sensitivity, resolution, and stability achieved with this quadruple resonance sample exchange probe, we have performed high precision distance measurements on the active site of the membrane protein bacteriorhodopsin. We also include a spectrum of the tripeptide N-f-MLF-OH at 100 K which shows 30 Hz linewidths.
DepartmentFrancis Bitter National Magnet Laboratory; Massachusetts Institute of Technology. Department of Chemistry; Massachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Plasma Science and Fusion Center
Journal of Magnetic Resonance
Barnes, Alexander B., Melody L. Mak-Jurkauskas, Yoh Matsuki, Vikram S. Bajaj, Patrick C.A. van der Wel, Ronald DeRocher, Jeffrey Bryant, et al. “Cryogenic sample exchange NMR probe for magic angle spinning dynamic nuclear polarization.” Journal of Magnetic Resonance 198, no. 2 (June 2009): 261-270.
Author's final manuscript