UNIFI Peptide Map: By what priority are the alternative peptide candidates displayed? - WKB111306

ENVIRONMENT

• UNIFI

ANSWER

If the “Alternate assignments” is Yes(True), by what priority are the alternative peptide candidates displayed?

In order for a peak to be assigned as a peptide,
firstly, the mass of the precursor ion must match the peptide (candidate sequence).

The acceptable mass shift threshold is set in the "Target match tolerance" of "Target by Mass" of the analysis method.

When there are multiple peptides (candidate sequences) that meet this condition,
sequences that are considered more probable are displayed as first choice
depending on how much the product ions are assigned as b-series or y-series,
the Assigned Intensity (%) value, and the mass deviation of precursor ions, etc. .

Specifically, assign with the conditions of A. and if the conditions of A. are the same, assign with the conditions of B.; if conditions of B. are the same, then assign with the conditions of C. ... and so on.

A. Types of peptides
→ Peptides hit by neutral loss or in-source decay have a lower priority.

B. Number of fragment ions
→ The one with the larger total number of hit b and y fragment ions has priority.

C. Order of modification
→ Peptides hit without modification have the highest priority, and modified peptides have priority in descending order of modification at the analysis method creation.

D. Mass shift
→ Priority is given to the smallest mass shift.

ADDITIONAL INFORMATION