Heteronuclear NOE

The heteronuclear NOE (hetNOE) experiment measures cross-relaxation between ¹H and a heteronucleus (typically ¹⁵N or ¹³C). It is widely used as a sensitive reporter of fast internal dynamics: rigid residues typically show hetNOE values close to the maximum (~0.8 for ¹H–¹⁵N at high field), while flexible regions show reduced or even negative values.

The NOE is measured as the ratio of peak intensities in a saturated and a reference spectrum:

\[\text{hetNOE} = \frac{I_\text{sat}}{I_\text{ref}}\]

Screenshot from heteronuclear NOE analysis

Usage

Provide paired reference and saturated spectra. reference and saturated can each be a single filename or a list of filenames — Bruker experiment numbers work too, individually or as a list/range; when lists are provided, results are averaged across all pairs.

using NMRAnalysis

# Single reference / saturated pair
hetnoe2d("expno1/pdata/231", "expno1/pdata/232")

# Multiple pairs (results are averaged across pairs)
hetnoe2d(
    ["expno1/pdata/231", "expno2/pdata/231"],  # references
    ["expno1/pdata/232", "expno2/pdata/232"],  # saturated
)

# Bruker experiment numbers
hetnoe2d(1, 2)

Output

Clicking Save to folder writes all results to results.csv. The derived columns are:

Column	Description
`hetnoe`, `hetnoe_err`	Measured hetNOE = Isat / Iref and uncertainty
`amp`, `amp_err`	Reference amplitude and uncertainty

See Peak Lists and Output Files for the full format. Plot the hetNOE against residue number with summaryplot("output-folder/").