Simultaneous 13C,15N-resolved NOESY

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Simultaneous 15N-, 13C(ali)-, 13C(aro)-resolved [1H,1H] NOESY

Modified from BioPack gnoesyCNhsqc.c by Main.AlexEletski, similar to the previous cnnoesy.c sequences by Youlin Xia and H. Atreya.

Requires pre-installed BioPack. BioPack power limits should be enabled on systems with cryogenic probes, otherwise wurst140 decoupling power is too high.

Make sure that 13C wurst decoupling power is 1 dB lower than the max rated decoupling power for the probe (wurst shape average is 80% of the max). 15N garp decoupling power must be 3 dB lower than the max rating.


Contents:

  • vnmrsys/psglib/gnoesyCaliCaroNhsqc.c
  • vnmrsys/parlib/gnoesyCaliCaroNhsqc.par/
  • vnmrsys/manual/gnoesyCaliCaroNhsqc
  • vnmrsys/templates/layout/gnoesyCaliCaroNhsqc/
  • vnmrsys/maclib/gnoesyCaliCaroNhsqc

Changes as compared to gnoesyCNhsqc and cnnoesy:

  • sw2N is the spectral width for 15N. Should be different from sw2 (13C)
  • 13C/15N t1 initial evolution is half-dwell only. The program will abort if f2180 is not set to 'y'. For testing purposes the initial evolution delay is set to a minimum if ni2=0.
  • Only adiabatic 13C inversion pulses are used. You can choose either stC140 or stC200. Composite inversion pulses are disabled.
  • Simultaneous high power pulses on 13C and 15N are avoided, therefore, peak power can be used.
  • Indirect 1H evolution modified to get correct initial points. Backward linear prediction is no longer required.
  • 15N inversion pulse changed to 90-180-90 composite. This should improve broadband performance at high fields, increasing the intensity of HE/NE strips of Arg, for example.
  • jnh parameter is introduced for 1J_NH coupling constant. The INEPT delays are now determined by jnh instead of jch.
  • jch is used to shift the 13C inversion pulses. The typical values are jnh=110 jch=155.
  • Added a flipN flag. Setting flipN='y' will invert the sign of 15N peaks.
  • Phase cycling is optimized for better axial peak and water suppression.
  • SEDUCE decoupling on carbonyls is not used, since it yield only small sensitivity gains while leading to significant resonance shifts.

Installation:

  • Save the gnoesyCaliCaroNhsqc.tar file into VnmrJ user home directory (e.g. /home/vnmr1).
  • Extract with tar xvf gnoesyCaliCaroNhsqc.tar - existing files will be overwritten!
  • cd to ~/vnmrsys/psglib/ directory and compile the pulse program by typing seqgen gnoesyCaliCaroNhsqc.c

Usage:

  • In VnmrJ run gnoesyCaliCaroNhsqc script to setup experiment
  • Record a 2D H-C/N plane first and optimize sw2, sw2N, dof and dof2, if necessary. Run calfa to find the optimal rof2 and alfa, acheiving zero first-order phase correction.
  • Set the desired mixing time, mix.
  • Use at least nt=4 for 3D acquisition, for best results use nt=8. The first two-step phase cycle suppresses axial peaks in the 13C/15N dimension, which is needed since 13C dimension is usually folded 3 times. The second two-step phase cycle suppresses axial peaks in the indirect 1H dimension. The third two-step phase cycle provides additional water suppression.


-- Main.AlexEletski - 26 Oct 2007

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