600 MHz Static Low-E Probe for Biological Solids

Purpose

PISEMA spectrum of 15N Leu (six sites) labeled 4 kDa trans-membrane protein sarcolipin, in oriented lipid bilayers. 1.5 mg of protein, 32 t1 increments x 2048 transients, B1 1H (decoupling) = 50 kHz, B1 CP = 67 kHz, Lee-Goldburg = 67 kHz.

We have two in-house built 600 MHz low-E static X—¹H probes for solid state studies studies of dielectrically lossy membrane protein samples (PISEMA, SAMMY). These probes are made to avoid RF-induced sample heating, which in conventional probes can destroy or irreversibly modify biological samples during milliseconds-long decoupling pulses. Additionally, electric field in lossy biological samples would otherwise seriously degrade ¹H channel efficiency, leading to insufficient decoupling. The low-E sample coil assembly [1] reduces presence of E-field inside the sample 10-fold, resulting in less heating and better sample stability for the duration of long experiments. Publications describing applications of these probes to protein structure determination [2-6] may be of interest to potential users.

Both probes allow swapping RF sample coils to suit different sample shape geometries (see tuning table below). A 7.5x5.5x11 mm flat coil is available for mechanically oriented proteins with RF fields of up to 100 kHz at ¹H and up to 70 kHz at ¹⁵N frequencies. A 90-degree rotated flat coil is also available for positioning such sample perpendicular to the static magnetic field. A sample coil with circular cross-section (5 mm ID) can be used for bicelle preparations with available fields of up to 100 and 80 kHz for ¹H and ¹⁵N respectively. Observe channel X can be retuned to other low-gamma nuclei of interest by swapping removeable chip capacitors.

Sample supplies for flat and bicelle coils

Sample Coils and Observe Nuclei

Procedure for switching coils and observe nuclei in static low-E probes, as well as physical location of chip capacitors mentioned below, is given on a separate page here.

If you have in mind detection of other nuclei, not listed in the table below, please contact Peter Gor'kov to see if they can be arranged.

600 MHz low-E probe #1

Flat coil, 7.5x5.5x11 mm

Isotope C8A C8B C7A C5A 15N 18 pF 15+1.8 pF 8.2 pF n/a

90-degree rotated flat coil, 7.5x5.5x11 mm

Isotope C8A C8B C7A C5A 15N 18 pF 15 pF 8.2 pF n/a

600 MHz low-E probe #2

Flat coil, 7.5x5.5x11 mm

Isotope C8A C8B C7A C5A 15N 18 pF 27 pF 8.2 pF n/a

Bicelle coil, ID = 5 mm

Isotope C8A C8B C7A C5A 15N 18 pF 15+1.8 pF 8.2 pF n/a 31P none none none n/a

Publications
    using this intrument

1.  P.L Gor'kov et al., J. Magn. Reson. 185, 77-93 (2007), PDF
2.  C. Li et al., J. Am. Chem. Soc. 129 (17) 5304-5305 (2007), PDF
3.  N.J. Traaseth et al., Biochemistry 45, 13827-13834 (2006), PDF
4.  J.J. Buffy et al., Biochemistry 45 (36), 10939-10946 (2006), PDF
5.  E.Y. Chekmenev et al., J. Am. Chem. Soc. 128, 5308-5309 (2006), PDF
6.  E.Y. Chekmenev et al., Biochim. Biophys. Acta 1758, 1359-1372 (2006), PDF