NCACX

Experiment Details

Dimensions = 3

Isotope labeling required = ¹³C and ¹⁵N

Magnetization transfer = magnetization originates on ¹H and is transferred to ¹⁵N, via cross polarization and then selectively to ¹³Ca nuclei through specific CP. DARR is then used to transfer magnetization to other neighboring ¹³Ca.Chemical shift evolves on ¹⁵N and ¹³Ca and detected on ¹³C.

Image courtesy: www.protein-nmr.org.uk/

Pulse program:

Comment on key optimization: (During spectrum acquisition)

CNST31 = wr;PLW14 = PLW12 found in DARR optimization

parmode = 2D; o1p = '100'; cnst22 = '55'; p2 = 2*p1; o2p = '3'; o3p = '115'; ZGOPTNS = '-DCDC' for constant duty cycle.

Example spectrum of GB1: Recorded with 3.2 mm rotor amd MAS @ 17857 Hz and 15 ms mixing time.

The spectrum gives ¹⁵N -¹³C correlation within the spin system.

References:

1. J. Pauli, M. Baldus, B.-J. van Rossum, H. de Groot and H. Oschkinat (2001) Chem. Biochem. 2 272-281.