Figure 2.

Comparison of four TiO₂-based phosphopeptide enrichment methods using different non-phosphopeptide excluders. (A) The strategy used to compare four different phosphopeptide enrichment methods using TiO₂ with different non-phosphopeptide excluders, including glutamic acid, lactic acid, glycolic acid, and DHB. (B) The profiles of the number of phosphopeptides identified and the phosphopeptide enrichment specificity of each method. Three replicates are performed for each method. (C) PCA analysis of the normalized intensities of phosphopeptides identified with the four methods. Each dot represents one replicate of the four methods. Samples from different methods are indicated by color. (D) The overlap between phosphopeptides identified with the four methods.