Sinc Shaped Band Selective Decoupling

Calibrate the decoupler for the probe to be used. Use CW off-resonance decoupling and measure the residual coupling constant. Use 'h2cal' macro to get gammaH₂ at a series of dpwr2 values. (assuming channel 3 is set to ¹³C)

Example:

dpwr2	gammaH₂
39	1695
40	1850
41	2043
42	2380
43	2624
44	2962

Choose the bandwidth of decoupling desired and divide by 1.3 to get the gammaH₂ to use.

Example: The C' chemical shift range in proteins is approximately 2500 Hz. So, the appropriate gammaH₂ value to cover this range is 2500/1.3 = 1923 Hz.

Set dpwr2 to the value, which most closely matches to the calculated gammaH₂.

Example: dpwr2 = 40, gammaH₂ = 1850 from the table in step 1.

Calculate dmf2 by multiplying gammaH₂ by a factor of 0.2472. Use the gammaH₂ value chosen in step 3.

Example: for dpwr2 = 40, dmf2 = 0.2472 * 1850 = 457.

Copy the shape file 'sinx.DEC' in shapelib. Set the following parameters:

dseq2 = 'sinx' dres2 = 1.0.

Set dm2 as appropriate for the status periods of the sequence.

Use the following procedure to calculate the decoupling profile for 'sinx' decoupling pulse with the parameters calculated using the instructions described above.

Sample : Uniformly ¹³C labeled amino acid solution. (We use a 50mM solution of mixture of Ala and Phe)
Pulse Sequence : 's2pul'. Set the spectrometer to observe ¹H.
Observe the ¹H spectrum without turning the decoupler on. The proton signals are split because of the coupling with bound carbon.
Set the decoupling parameters for the ¹³C channel as calculated from the instructions described above. Set up an array for dof2 ranging from 10000 Hz to -10000 Hz with an increment of -500 Hz. This will allow scanning of ¹³C frequencies from carbonyl to methyl region.
Splitting of proton signal will disappear when the decoupling pulse covers the frequency of ¹³C nuclei coupled with that proton. The range of dof2 values, which removes the splitting of the proton signal gives the bandwidth of the decoupling pulse.

Example: