The assignment panel popup displays all the possible assignment options for the last selected peak. The assignment panel allows the connection of resonances, displayed in a ranked list, to each dimension of the selected peak. Resonance assignments to peaks can be removed and replaced. The popup also allows the assignment of a resonance to a given set of atoms in conjunction with the Molecules: Atom Browser popup.

The Assignment: Assignment Panel popup.

Structure

Assignment possibilities are made either based on chemical shift matches or on H-H distances in NOESY spectra. The [Structure] option specifies which structure as a reference of H-H distances that are used to create the list of assignment possibilities for the selected peak.

Assignment possibilities tables

This table is split into rows, 1 for each dimension in the peak, each which contains a left hand table and a right hand table.

Each left hand table header displays the dimension, isotope and position of the peak in that dimension, and the table contains contains the assignments to atoms and resonances for the peak in this dimension, e.g.:

• F1 1H 9.7438

  • 8CysH

  • [1922]

• F2 15N 123.1998

  • 8CysN

  • [1920]

If desired, a new resonance can be created with the [<New>] button for any dimension at any time.

The right hand tables display the resonances to which the peak dimension could be possibly assigned. The resonances present in these tables are determined by the assignment tolerances (set via Experiments: Edit Spectra, tab {Tolerances}) and the options set in the popup.

An assignment of a resonance to a peak is made by clicking on one of the resonance possibilities in the right hand table. Assignments can be added or replaced:

• • To add an assignment click on the assignment possibility in the right hand table or by creating a new resonance using the [<New>] button.

  • To replace an assignment click on the peak assignment in the left hand table that is to be replaced, and then click on the new assignment possibility in the right hand table. The assignment can also be replaced by a new resonance by clicking the [<New>] button after selecting the assignment.

Multiple resonances assigned to a peak dimension indicate that the peak is ambiguously assigned or assigned to both/all resonances. This is common where a peak originates from the resonances of two sets of atoms with unresolvable chemical shifts. For example, unresolvable lysine delta hydrogens (Hd*) means the connection to both Hd2 and Hd3 atoms.

By default the resonances in the right hand table are ordered in terms of difference in chemical shift to the position of the peak dimension (delta). However if a structure (preliminary or otherwise) is active within the current project, hydrogen resonance possibilities may also be sorted in to order of distance (of any assigned atoms) given the structure. 

#

The number of the resonance of the assignment possibility.

Name

The name of the resonance or the atom assignment of the assignment possibility.

Delta

The difference in chemical shift between the selected peak and the assignment possibility in the given dimension.

Shift

The chemical shift of the assignment possibility in the given dimension.

SD

The standard deviation of the chemical shift of the assignment possibility in the given dimension.

Dist

The distance, if displayed, is the distance between the assignment possibility and any resonance assigned to a specific hydrogen in the next hydrogen dimension. The average position is used if multiple resonances are assigned to a dimension.

Aliased Possible

If selected, the list of possible resonances includes those that may be assignable to the peak dimension  if the position of the peak in this dimension were unaliased. Such resonance options are coloured yellow in the right hand table.

If a peak dimension is then connected to one of these resonances its aliasing will be appropriately set, i.e. its position will be unaliased so that the position of the peak closely matches that of the assigned resonance.

Restrict Mol System

If selected, the list of possible resonances are restricted to those within the molecular system.

Intra-residue

If selected, this option restricts the list of assignment possibilities to intra-residue assignments.

Correlated Dims

If selected, this option restricts the list of assignment possibilities according to the correlations of the different dimensions in the spectrum. For example, in case of a 15N-NOESY-HSQC, if the Hn proton is assigned to a specific amide proton, the options for the 15N dimension are restricted to the N that is bound to the assigned Hn.

Double Tolerances

If selected, this option temporarily doubles the peak dimension assignment tolerances for the purposes of increasing the number of resonance possibilities (within tolerances) displayed for each of the peak dimensions.

Labelling Scheme

Selects the isotope labelling scheme to be used for the prediction of the peaks. See also Molecules: Isotopomer Schemes.

Min Isotope Fraction

Specifies the minimum isotope fraction in the selected labelling scheme.

(Re) Assign

This button opens the Molecules: Atom Browser popup to assign the selected resonance to an atom.

Set Atom Type

This button opens the Molecules: Atom Browser popup to assign the selected resonance to an atom type. In order to assign an atom type, e.g. a Cg, you can pick any Cg in the list of atoms in the atom browser.

Deassign

This allows a selected resonance to be cleared of any atomic or spin system assignments. If the user confirms to clear atomic assignments the user will then be prompted to clear the spin system assignments (Query popup). In this way a resonance can be disconnected from an atom but left in a given residue of spin system.

Clear contrib

Removes the selected resonance from the list of peak contributions. Clearing a contribution leaves the assignment of the resonance to any atoms unchanged.

Tentative Assign

This allows the user to make a tentative assignment. This means that the assignment is not certain, and the assignment is indicated with a question mark, e.g. 1?MetHA[1921], in which the tentative assignment for the peak is made to the HA of Met 1, resonance 1921.

Set Same Spin System

This allows the user to set peak assignments to a single spin, if possible. In the case of multiple spin system possibilities, the user is asked to whether to merge the spinsystems and any possible resonance duplications. Use with care.

Show On Structure

Highlights any atoms assigned to the peak on the a selected structure in the Structure: Structure Viewer popup. If the peak has hydrogen atom assignments in two dimensions then this will be shown as a connection on the structure. If there is one hydrogen dimension fully assigned then all of the atomic assignment possibilites for any unassigned hydrogen dimension will be displyed as connections. Such connections will be coloured according to distance: <5.5 A; green, 5.5-8.0 A; yellow, >8.0 A; red.

Show Peaks

Shows the peaks for the selected assignment in the Peaks: Selected Peaks popup.

Merge <dimension> Resonances

This option will merge all of the resonances assigned to the peak in the dimension of the currently selected resonance into one single resonance. Any resonances that the user does not wish to merge can be removed first from the peak dimension using the [Clear Contrib] option, and then re-assigned after the merge.