Fig. 5. Susceptibility of Ca(ii)-bound CP-Ser, I60E, and I60K (30 μM) to degradation by HNE (0.3 μM). (A) Representative HPLC traces illustrating the full-length S100A8 and S100A9 subunits following incubation with HNE for 0–4 h at 37 °C (75 mM HEPES, 100 mM NaCl, ±1.5 mM CaCl₂, ±30 μM MnCl₂, pH 7.5). (B) Reduction in the S100A8 and S100A9 integrated peak areas (normalized to initial peak areas) as a function of time (mean ± SDM, n = 3). Full chromatograms are given in Fig. S13.† .