The influence of oxidation by 2,2-Azobis[2-amidinopropane]dihydrochloride (AAPH)-generated free radicals on immunoglobulin G (IgG) stability was investigated using differential scanning fluorimetry (DSF), real-time isothermal differential scanning fluorimetry (RT-iDSF), and pulse proteolysis. A, Thermal shift changes (ie, change in T m ) determined by DSF for human IgG (1 mg/mL) incubated with {0, 2.5, 5, 10, 25, or 50} mM AAPH for 1 hour at 4°C. B, The effect of oxidation on the velocity of denaturation of IgG by urea as determined by RT-iDSF. Immunoglobulin G samples were incubated with or without 50 mM AAPH for 2 hours at 4°C immediately prior to assaying. An asterisk (*) indicates significantly different from the control value ( P