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 | |||
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Copyright: Harvard Medical School | |||
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Introduction
Please see CAN concept document for more explanation of this experiment.
Delays
- d1 - recycling delay [1.6s]
- d16 - gradient recovery delay [200μs]
Constants
- 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
Gradients
- 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
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
sp23
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
sp25
180o refocussing pulse for 13C.
- p11 - length [320μs]
- sp25 - power level
- spnam25 - waveform - Q5tr.1000
Decoupling
Default lengths of decoupling given here are for 500 MHz instrument.
cpd2
Used to decouple 1H - protons.
- pl12 - power level
- pcpd2 - duration of the 90o pulse for waltz16 [80μs]
- cpdprg2 - decoupling program waltz16
cpd3
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
cpd4
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]
References
- 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
Categories: Pulse sequences | Liquids | Bruker | Wagner Lab | 15N detected | 2D | Sample requirements | 1H | 2H | 13C | 15N | 500 MHz