Figure 2 | Scientific Reports

Figure 2

From: Oxidation of protein-bound methionine in Photofrin-photodynamic therapy-treated human tumor cells explored by methionine-containing peptide enrichment and quantitative proteomics approach

Figure 2

Workflow for Met oxidation profiling in A431 cells treated with different Photofrin-PDT regimens. SILAC-labeled A431 cells were preloaded with Photofrin (as photosensitizer, PS) under three different incubation conditions (conditions I-III), and treated with or without laser irradiation to generate paired control and PDT cell groups, respectively. Equal amount of protein extracts from the control and PDT groups were mixed at a 1:1 ratio and digested with trypsin. Each digested sample was divided into two parts; one part was directly analyzed by 2D-LC-MS/MS (LTQ-Orbitrap), while the other was subjected to iodoacetyl-PEG2-biotin-mediated Met-peptide enrichment, followed by the same 2D-LC-MS/MS analysis. A label-swap replication of the SILAC experiment was applied to each condition. The Protein Discoverer software (Thermo Scientific) was used to combine and analyze the MS data from all 12 runs.

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