Exercise MSMS4: answers
- Are all four reporter ions being used?
No, looks like only 114 and 116 labels were used
- Why are some ratios shown in bold face?
These are ratios that are significantly different from 1.
(details)
- Would normalisation a good idea for this example?
Definitely not. All the indications are that this is a test sample with a ratio of approx 1:2.
Normalisation should only be used when the average ratio is expected to be 1.
- How is iTRAQ modification to Tyr used in the method?
Any match with iTRAQ(Y) is excluded from quantitation because this reaction is slower
than iTRAQ (K) and iTRAQ (N-term), so likely to be incomplete, which could give a skewed ratio.
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