Exercise SQ2: answers
Correct tag syntax is
703.74 etag(147.07, PS[I|L]T[I|L]FD, 920.41)
or
703.74 etag(147.07, PS[IL]T[IL]FD, 920.41)
- What is the peptide sequence?
ALAGCDFLTISPK
- Are there any alternative solutions?
- If so, how do you choose a preferred solution?
By trying to find reasonable explanations for the observed mass differences.
In the case of +70.77 Da, this could be cysteine alkylation by free acrylamide in the gel (+71.04 Da). The modification is propionamide
There isn’t any single modification in Unimod that would give a delta of +74.72 Da +/- 0.5.