1D NOESY for Bruker (selnogp)

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Basic facts about selnogp

Synopsis: DPFGSE selective 1D NOESY

Family: DPFGSE 1D NOESY

Code authors:

Copyright: Bruker, Inc.

Introduction

The selnogp is a pulse sequence for Bruker epuipment. It is a selective 1D version of 2D NOESY using excitation sculpting technique with simple pulsed field gradients (PFG). this experiment can be used in place of traditional NOEDiff.

Standard parameters might be accessible on your system under name SELNOGP. If so, then typing rpar SELNOGP will load them, and only RF-pulse parameters will need to be adjusted.

This pulse sequence uses a single DPFGSE element for the selective excitation.

Delays

d1 - recycling delay (1-5 x T1)

d8 - mixing time (can be 500 ms for small molecules or 100 ms for larger molecules, such as peptides or proteins)

An NOE build up curve may be obtained by varying d8 from small to larger values.

d16 - gradient recovery delay (depends on the probe) may be on the order of 100-200 μs.

Carrier frequencies

O1 (or O1P for the value in ppm) is the carrier frequency used for the hard pulses.

Parameter spoffs2 - may be used as an offset for the selective excitation.

If O1 is set exactly at the selectively excited resonance, then spoffs2 must be zero.

In most cases it will be more optimal to set O1 at the center of spectrum and enter spoffs2 as a difference in Hz between the resonance of interest and the carrier frequency applied to the hard pulses.

Hard RF pulses

p1 - ¹H 90^o pulse at power level pl1

Hard pulses are applied at O1 (or O1p) carrier frequency.

Selective RF pulse

There is one shaped selective pulse with the following adjustible parameters:

Note: pl0 must be at 120.

• p12 - length (default 80 ms, but generally length should be chosen according to desired selectivity)
• sp2 - power level
• spnam2 - waveform file name (default Gaus1.1000 - gaussian pulse with 1000 steps. Can be used a gaussian curve with 5% truncated to increase selectivity)
• spoffs2 - offset in Hz relative to O1 - the carrier frequency

p12 can be adjusted to the shortest value producing clean "parent" excited resonance signal at mixing time=0.

Gradient pulses

• p16 (default 1 ms) - length used for the gradient pulses gp1 and gp2
• gp1 and gp2 strengths of the two gradient pulses.
• gpnam1 and gpnam2 - shapes of gradient pulses (default - SINE.100)

Suggested ratio of gp1/gp2 - 15/40

References

H. Kessler, H. Oschkinat, C. Griesinger & W. Bermel,

J. Magn. Reson. 70, 106 (1986)

J. Stonehouse, P. Adell, J. Keeler & A.J. Shaka, J. Am. Chem. Soc 116,

6037 (1994)

K. Stott, J. Stonehouse, J. Keeler, T.L. Hwang & A.J. Shaka,

J. Am. Chem. Soc 117, 4199-4200 (1995)