Cathepsin G rapidly cleaves Aβ_1–42.

<p>(a) MALDI-TOF spectra of Aβ_1–42 incubated alone (red) or with cathepsin G (green) at t≈0.25 min. Peaks are labeled with mass-to-charge ratios (m/z), and mass is in Daltons (Da). A peak of 4500 Da, which represents intact Aβ_1–42, appears in all Aβ_1–42 spectra. Peaks predicted to represent Aβ_1–42 fragments at 2072 Da, 2001 Da, and 1844 Da are already present after incubation with cathepsin G at t≈0.25 min (green). Cathepsin G incubated alone is shown in blue, and no peak at 4500 Da is exhibited by cathepsin G. (b) MALDI-TOF spectra at t = 15 min. Note the absence of the full Aβ_1–42 peak and the presence of products at 2072 Da, 2001 Da, and 1844 Da as well as an additional fragment peak at 1476 Da when Aβ_1–42 incubated with cathepsin G (green). (c) Graph shows relative % peak intensity of Aβ_1–42 and its fragments (intact Aβ_1–42 + Aβ_1–42 fragments at each time point) analyzed at t≈ 0.25 min, t = 5 min, t = 15 min, t = 30 min, and t = 60 min. Data are representative of 3 independent experiments.