Oriented sample solid-state NMR (OS-ssNMR) spectroscopy is uniquely suited to determine membrane protein topology at the atomic resolution in liquid crystalline bilayers under physiological temperature. However, the inherent low sensitivity of this technique has hindered the throughput of multidimensional experiments necessary for resonance assignments and structure determination. In this work, we show that doping membrane protein bicelle preparations with paramagnetic ion chelated lipids and exploiting paramagnetic relaxation effects it is possible to accelerate the acquisition of both 2D and 3D multidimensional experiments with significant saving in time. We demonstrate the efficacy of this method for a small membrane protein, sarcolipin, reconstituted in DMPC/POPC/DHPC oriented bicelles. In particular, using Cu2+-DMPE-DTPA as a dopant, we observed a decrease of 1H T1 of sarcolipin by 2/3, allowing us to reduce the recycle delay up to 3 times. We anticipate that these new developments will enable the routine acquisition of multidimensional OS-ssNMR experiments.
Bibliographical noteFunding Information:
This research is supported by the National Institute of Health (GM 64742 to G.V.). We would like to thank Bethany Pertzsch for helping with SLN expression and purification, Dr. Daniel Weber and Erik Larsen for critical reading of this manuscript.
© 2017 Elsevier Inc.
- Oriented sample solid-state NMR
- Paramagnetic relaxation enhancements
- Sensitivity enhancement
- Separated local fields