To further evaluate the selectivity, we used mass spectrometry-based proteomics analysis. Analysis of the sample derived from the above cell lysates supplemented with mSA and ClpP detected 1410 proteins. In the presence of compound 1, mSA and 33 other proteins (2.4%) were decreased (Figure and Table ). Furthermore, in the presence of biotin as a competitor with 1, the abundances of 4 proteins, including mSA, were increased compared to the sample prepared in the absence of biotin.