MALDI-MS Patterning of Caspase Activities and Its Application in the Assessment of Drug Resistance

Mass spectrometry (MS) has been widely used for Enzyme activity assays. Herein, we propose a MALDI-MS patterning strategy for the convenient visual presentation of multiple Enzyme activities with an easy-to-prepare chip. The array-based caspase-activity patterned chip (Casp-PC) is fabricated by hydrophobically assembling different phospholipid-tagged peptide substrates on a modified ITO slide. The advantages of amphipathic Phospholipids lead to high-quality mass spectra for imaging analysis. Upon the respective cleavage of these substrates by different caspases, such as Caspase-1, -2, -3, and -8, to produce a mass shift, the Enzyme activities can be directly evaluated by MALDI-MS patterning by m/z-dependent imaging of the cleavage products. The ability to identify drug-sensitive/resistant Cancer cells and assess the curative effects of Anticancer drugs is demonstrated, indicating the applicability of the method and the designed chip.

MALDI-MS; caspases; enzymes; high-throughput screening; mass spectrometry.