Evidence that the ProPerDP method is inadequate for protein persulfidation detection due to lack of specificity.

Protein persulfidation (protein-SSH) is a previously unidentified type of modification found in both eukaryotic and prokaryotic cells in recent years. Although a few persulfidated proteins have been identified, analyzing protein persulfidation from a proteomic level is still a big challenge. ProPerDP is a persulfidation detection method recently reported in Science Advances. The authors claimed that this method could specifically detect persulfidated proteins of cell lysate with minor false-positive hits; hence, it could be used for proteomic-level analysis of protein persulfidation. However, when using this method for Escherichia coli cell lysate analysis, we found that the percentage of false-positive hit was >90%. We performed a systematic study on this method and discovered that iodoacetyl-PEG2-biotin tag mislabeling is the reason causing this low specificity. We concluded that the ProPerDP method is completely inadequate for persulfidation analysis. The previous findings based on the ProPerDP method need to be reinvestigated.