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Chemical screening by mass spectrometry to identify inhibitors of anthrax lethal factor


Mass spectrometry (MS) analysis is applicable to a broad range of biological analytes and has the important advantage that it does not require analytes to be labeled. A drawback of MS methods, however, is the need for chromatographic steps to prepare the analyte, precluding MS from being used in chemical screening and rapid analysis. Here, we report that surfaces that are chemically tailored for characterization by matrix-assisted laser-desorption ionization time-of-flight MS eliminate the need for sample processing and make this technique adaptable to parallel screening experiments. The tailored substrates are based on self-assembled monolayers that present ligands that interact with target proteins and enzymes. We apply this method to screen a chemical library against protease activity of anthrax lethal factor, and report a compound that inhibits lethal factor activity with a Ki of 1.1 μM and blocks the cleavage of MEK1 in 293 cells.

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Figure 1: SAMDI-based screen for lethal factor toxin.
Figure 2: Dose-response curve from the SAMDI assay.
Figure 3: Kinetic characterization of DS-998.
Figure 4: Activity of DS-998 in cellular assays.
Figure 5: Inhibition of lethal factor–induced macrophage death by DS-998.
Figure 6: Z′-factor for the SAMDI assay.


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This work was supported by the National Science Foundation, the Ludwig Fund for Cancer Research and a Burroughs Wellcome Graduate Fellowship to D.-H.M.

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Correspondence to Milan Mrksich.

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Min, DH., Tang, WJ. & Mrksich, M. Chemical screening by mass spectrometry to identify inhibitors of anthrax lethal factor. Nat Biotechnol 22, 717–723 (2004).

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