Experiment Details
Dimensions = 3
Isotope labeling required = 13C and 15N
Magnetization transfer = Establishes correlation between 13COi−1 to 13Cαi and 15Ni with single quantum coherences evolving simultaneously on the COi, Ni
Magentization is generated on 1H and transferred to 13C via CP. 13C chemical shift evolves during t1. Band selective 13COi-1 to 15Ni is obtained via spin lock on 15N and ramping through the specific CP matching on the 13C channel. The magentization then evolves on 15N during t2 followed by transfer to 13Cαi and detection.
Pulse program:
2001, Griffin et. al.
Comment on key optimization:
ZGOPTNS = '-Dnomix';cnst22 = '55'; cnst21 = '175; p2 = 2*p1; p22 = 2*p21;
parmode = 3D; o1p = '100'; o2p = '3'; o3p = '115'; ZGOPTNS = '-DCDC' for constant duty cycle
Example spectrum (20011, Griffin et.al): The 3D spectrum correlates the ( 13CO i−1 ) to ( 15N i ) and ( 13Cα i ) when t1 and t2 are incremented independently.
Left figure: Contour plot of a sample of peptide U-[ 15 N, 13 C]-N-Acetyl-Valine-Leucine (VL) acquired with t 2 = 0. ω 1 =( 15 N i ) and ω 3 = ( 13 Cα i )-the valine at ω 1 = 123.9 ppm, ω 3 = 58.7 ppm and the leucine at ω 1 = 129.1, ω 3 = 57.1 ppm.
Right figure:Same expt with simultaneous incrementation of t1 and t2 evolution periods. The peaks split into doublet centered in 15Ni