Fig. 8.

A library of synthetic peptides identifies a candidate MMP-9 cleavage site in β₂ integrin. A, a library of 10 overlapping peptides based on the extracellular domain of β₂ integrin adjacent to its putative transmembrane region was synthesized. B, each synthetic peptide was incubated in PBS with or without active MMP-9. Reaction mixtures were subjected to MALDI-TOF-MS. This approach demonstrated that a single peptide, ECVKGPNVAAIVGGT, was cleaved proteolytically between Ala and Ile to yield a product peptide of m/z 987. C, MALDI-TOF/TOF analysis of the cleavage product.