Label-free quantification with DISPA using standards. (A,B) Scatterplot of peptide fragment intensities from
two injections of the MS-QCAL protein (A) and HeLa peptides (B). (C,D) Quantification curve of a standard peptide
angiotensin I (C) and MS-QCAL protein (D) at different concentrations.
(E,F) Peptide (E) and protein (F) quantities
determined by DISPA-LFQ from a dilution series of the HeLa proteome.
The shaded area represents one standard deviation from the mean in
the middle. Only peptides or proteins with positive slopes were plotted
in either set, which excludes 60 peptides or 18 proteins before the
Pearson test for good slope (p value < 0.05) or
3 peptides and zero proteins after the Pearson test for slope (p value < 0.05). Significant peptides or proteins were
defined as those with a p value from the Pearson
correlation of less than 0.05. (G,H) Examples
of well-quantified peptide (G) and protein (H).