Extracellular matrix metalloproteases (Matrix Metalloproteases, MMPs) are proteolytic enzymes that are generally expressed at low levels in healthy tissues, but whose expression increases during physiological or pathological tissue remodeling processes (inflammation, injury, etc.). Under these conditions, they contribute to various processes, including angiogenesis, tissue repair, embryogenesis, and skin wound healing. Approximately 23 MMPs are found in humans, encoded by different genes and produced by numerous cell types.
To study their functional state within complex proteomes, tools such as activity-based protein profiling (ABPP) have been widely used. However, with ABPP probes, it is generally necessary to perform a protein enrichment or isolation step before the protein can be analyzed, which limits sensitivity and prevents the simultaneous (multiplexed) analysis of numerous samples.
AN ORIGINAL CHEMO-PROTEOMICS APPROACH FOR THE DETECTION OF ACTIVE MMPs
In this study, the authors present an original enrichment-free chemoproteomic approach for the direct detection, by MALDI mass spectrometry (Matrix-Assisted Laser Desorption/Ionization), of metalloproteases in their active form across multiple biological samples. An affinity probe targeting the active site of MMPs enables the transfer, through a proximity reaction, of a mass tag that allows the detection of labeled signature fragments following proteolytic digestion. This specific labeling greatly enhances the detection and unambiguous identification of MMPs in complex proteomes, yielding a set of observed signature peptides that defines an activity fingerprint.
This innovative approach, which combines chemical selectivity with analytical simplicity, establishes a robust platform for activity-based enzyme detection. The team is currently working to establish the activation profile of several metalloproteases in synovial fluids from patients with osteoarthritis, a condition for which the “single-biomarker strategy" has shown its limitations. Research is now focusing on identifying a panel of biomarkers that could better reflect a specific stage of the disease, its severity, and its progression.
Graphical abstract (cover page)
Ionized by the mass spectrometer's laser, the peptides labeled by the chemical probe (shown in yellow), derived from active proteases, appear as intense signals in the mass spectra, revealing distinct activity fingerprints and providing functional indicators. Adapted from Berthy et al., Angew. Chem. Int. Ed. 24/2026. Image design : Monika Kaminska
Joliot Institute contact : Laurent Devel (laurent.devel@cea.fr)
Sometimes referred to as the intercellular cement, the extracellular matrix is a collection of macromolecules located between cells in connective tissue that facilitates cell–cell interactions and adhesion and organizes cells into tissues. It therefore controls crucial functions such as cell proliferation, survival, migration, and differentiation.