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Experiment Details
Dimensions = 2
Isotope labeling required = 13C
Magnetization transfer = magnetization originates on 1H and is transferred to 13C which is the transferred to 13C nuclei close in space. Long mixing times are beneficial in achieving inter-residue contacts needed in assignments and three dimensional structure calculations.
Image courtesy: www.protein-nmr.org.uk/
Pulse program: hCC.cp
Parameters:
p1 : C 90 at pl1
p3 : H 90 at pl2
p15 : HC CP at sp41 (f1,C) and sp40 (f2,H)
p21 : N 90 at pl21 (-DTC)
p22 : N 180 at pl21 (-DTC)
pl1 : C pulse power (-DC90)
pl2 : H pulse power
pl12 : H dec power
pl14 : H DARR power (= 1*cnst31 (MAS freq); for PDSD = 0 W)
pl21 : N pulse power
sp40 : H CP power
sp41 : C CP power
d0 : incremented delay (t1)
d1 : recycle delay; 1 to 5 times T1
d8 : PDSD/DARR mixing time
d30 : extra time for constant duty cycle
pcpd2 : pulse length in decoupling sequence cpdprg2
cpdprg2 : spinal64, swftppm, tppm etc. decoupling program
spnam40 : H ramp use e.g. ramp.10070 for variable amplitude CP
spnam41 : C ramp use e.g. square.100 for square pulse CP
cnst30 : expected td1 for use in constant duty cycle (-DCDC)
cnst31 : MAS rotation rate in Hz
inf1 : 1/SW(C) = 2 * DW(C)
in0 : = inf1
in30 : = inf1
l0 : loopcounter for F1
l1 : loopcounter for mixing time
ZGOPTNS : -DCDC : for constant duty cycle
-DDP : direct C excitation
-DTC : probe in triple channel mode
-Dlacq : aq is longer than 50 ms
or blank
FnMODE: TPPI, States or States-TPPI
ns: MIN. 4 (full:16)
Comment on key optimization:
CNST31 = wr;PLW14 = PLW12 found in DARR optimization (above);ZGOPTNS = '-DCDC' for constant duty cycle
Example spectrum of GB1: Recorded with 5 ms, 20 ms and 500 ms mixing time respectively in a 1.9 mm rotor and MAS @ 13333 Hz. The spectrum gives 13C-13C correlation.
5 ms mixing
20 ms mixing
500 ms mixing
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