Fig. 6.

Panel A: the presence of dextran modulates the changes in molecular mass of β-casein, ubiquitin and melittin (each 500 μM) induced by AAPH-derived ROO•. β-Casein (lanes 1–3), ubiquitin (lanes 4–6) and melittin (lanes 7–9) were incubated with 100 mM AAPH at 37 °C under 20% O₂ in phosphate buffer (200 mM, pH 7.0) in the absence and presence of 60 mg mL⁻¹dextran. SDS–PAGE was run, under non-reducing conditions, on 4–12% Bis-Tris acrylamide gels, with 12 μg of protein loaded per well. Panel B: Detection of di-Tyr formation by immunoblotting. Gels from Panel A were blotted to a PVDF membrane as described in the Materials and methods section and probed with an anti-diTyr primary monoclonal antibody. MM: molecular mass markers, with masses indicated on the left-hand vertical axis. Lanes 1, 4 and 7 correspond to control samples of each protein incubated in absence of AAPH, whilst lanes 2, 5 and 8, and 3, 6 and 9 correspond to samples incubated with AAPH in absence, and presence of dextran, respectively. Each gel image or blot is representative of one of three independent experiments carried out on different days.