Assign

The Assign menu provides direct access from a spectrum window to the most common assignment functions in Analysis.

Assign peak

Opens the Assignment: Assignment Panel popup. This popup provides the primary means to make peak assignments, and works together with the Molecules: Atom Browser popup. It displays the possible assignment options and the assignment status for a given selected peak. The information in the assignment panel is displayed for the peak that was last selected and updated every time another peak is selected.

Propagate assignments

This option can be used to copy assignments from an assigned peak to other, unassigned, peaks. The assignments are copied where possible and within assignment tolerances, to all of the selected peaks. Any resonances that were assigned to the selected peaks will be assigned to any other valid peak dimension within the selection. Useful for quickly assigning multiple peaks which, for example, derive from the same 15N and 1H amide resonances.

Add to spin system

This option adds the resonances that were assigned to the currently selected peaks to a spin system. If the peaks have no spin system information a new spin system will be created. If only one spin system is represented by the peak assignments, all of the resonances assigned to the peaks will be added to this spin system. If multiple spin systems are represented these may be merged together or the operation canceled.

Predict Spin System Type

Opens the Spin System Type Scores popup. This popup provides the functionality to predict amino acid types from protein spin systems, which is a powerful tool in the protein assignment process. The tool uses the chemical shift and atom type information of resonances in a spin system and compares these to reference chemical shift databases to predict the type of amino acid. Predictions can be performed on an individual spin system basis. If many spin systems are assigned only the first, according to the order of the peak dimensions, is considered.

See also: Resonance: Spin System Types

Deassign selected peaks

This option removes all resonance assignments from the currently selected peaks.

Set sequential spin systems

Allows the user to specify the sequential relationship of the spin systems in the assignment of a selected peak belong. For example the user may choose the option

F1 0, F2 -1, F3 0

to set the spin systems for an HN(CO)Ca peak, of which the 13C (F2) resonance is known to originate from the previous residue (i-1), and the 1H (F1) and 15N (F3) resonances from residue (i).

Clear all sequential links

Clears all the sequential links for the spin systems that the peak was assigned to.