CAN for Bruker - pulse sequence to correlate CA and N (Wagner Lab)

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Basic facts about n_can_2h_ct_2d_ul.kt

Synopsis: CAN - 15N detected pulse sequence to correlate amide Ni with Cαi and Cαi-1

Family: CAN

Sample requirements: Uniformly D,13C,15N labeled

Code authors:

 Gerhard Wagner, Koh Takeuchi

Copyright: Harvard Medical School

Hardware requirements:

 HCND probe, optimized for 15N and 13C detection


Please see CAN concept document for more explanation of this experiment.


  • d1 - recycling delay [1.6s]
  • d16 - gradient recovery delay [200μs]


  • cnst21 - average chemical shift of CO atoms [176]
  • cnst22 - average chemical shift of CA atoms in ppm [55]

Acquisition dimensions

  • aq - acquisition time in directly detected 15N dimension

Carrier frequencies

  • o1p - 15N - center of amide nitrogen region
  • o2p - 1H - water resonance ~4.7 ppm
  • o3p - 13C - center of Cα region [55ppm]
  • o4p - 2H - water resonance ~4.7 ppm

Hard pulses

  • p1 - length of the hard 90o pulse for 15N
  • pl1 - power level for p1 pulse


  • p16 - length of the gradient pulse [1ms]
  • gpnam1 - name of the gradient waveform [SINE.100]
  • gpz1 - strength of z gradient - 10 G/cm ~[20]%
  • gpx1 - 0
  • gpy1 - 0
  • d16 - gradient recovery delay [200μs]

Shaped pulses

Power level for the shaped pulses needs to be calibrated with the stdisp tool.

There are five shaped pulses in this pulse sequence: sp15, sp23, sp24, sp25 and sp26.

Offsets for the shaped pulses are 0 Hz except sp26 and sp15


This pulse is used as a part of the cpd3 (mlevsp180) decoupling program

The waveform employed is wurst frequency swept adiabatic inversion pulse.

Frequency sweep - 40 kHz, duration 2ms - specific to 500 MHz instrument.

The purpose of this pulse is to simultaneously decouple CO and CA.

  • pcpd3 - length 2ms
  • pl16 - power level - not sp15 - because this pulse is a part of composite pulse decoupling program
  • spnam15 - waveform wurst-40k-2ms.kt - included with this record
  • spoffs15 - offset for the pulse sp15 - 115.5 ppm - the middle of CO and CA chemical shift


90o excitation pulse for 13C.

  • p11 - length [320μs]
  • sp23 - power level
  • spnam23 - waveform Q5.1000

sp24 and sp26

180o inversion pulse for 13C.

  • p12 - length [256μs]
  • sp24, sp26 - power levels
  • spnam24, spnam26 - waveform Q3.1000
  • spoffs26 - offset for pulse sp26 - center of carbonyl (CO) region in Hertz


180o refocussing pulse for 13C.

  • p11 - length [320μs]
  • sp25 - power level
  • spnam25 - waveform - Q5tr.1000


Default lengths of decoupling given here are for 500 MHz instrument.


Used to decouple 1H - protons.

  • pl12 - power level
  • pcpd2 - duration of the 90o pulse for waltz16 [80μs]
  • cpdprg2 - decoupling program waltz16


See setup for the shaped pulse sp15 as mlevsp180 program uses shaped pulse sp15

  • cpdprg3 - program for decoupling [mlevsp180]
  • pl16 - power level used by the waveform assigned to spnam15


Deuterium (2H) decoupling.

  • pl17 - power level for the 90o within the decoupling program
  • pcpd4 - length of the 90o within the decoupling program [250μs]
  • cpdprg4 - program for decoupling [waltz16]


  1. Takeuchi, K and Heffron, G and Sun, ZYJ and Frueh, DP and Wagner, G. Nitrogen-detected CAN and CON experiments as alternative experiments for main chain NMR resonance assignments. Journal of Biomolecular NMR pp. 1--12. BibTeX [cancon]
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