# hncaco.m

Protein-specific HN(CA)CO experiment (Figure 7.41 of "Protein NMR Spectroscopy", 2nd edition) using pre-set values of J-couplings used in the magnetisation transfer stages. The simulation uses the bidirectional propagation method described in (http://dx.doi.org/10.1016/j.jmr.2014.04.002).

## Syntax

    fid=hnca(spin_system,parameters,H,R,K)


## Arguments

   parameters.npoints     - a vector of three integers giving the
number of points in the three temporal
dimensions, ordered as [t1 t2 t3].

parameters.sweep       - a vector of three real numbers giving
the sweep widths in the three frequen-
cy dimensions, ordered as [f1 f2 f3].

H   - Hamiltonian matrix, received from context function

R   - relaxation superoperator, received from context function

K   - kinetics superoperator, received from context function


## Outputs

    fid - three-dimensional free induction decay


## Examples

Below is the output (3D spectrum and three projections) of the HN(CA)CO pulse sequence for the GB1 protein (examples/nmr_proteins/hncano_gb1.m).

## Notes

1. The sequence is hard-wired to work on 1H,13C,15N proteins and uses PDB labels to select spins that will be affected by otherwise ideal pulses.
2. Channels: F1 is 15N, F2 is 13C, F3 is 1H.
3. Spin labels must be set to PDB atom IDs ('CA', 'HA', etc.) in sys.labels for this sequence to work properly