Absorbance spectra and electrophoresis of native BSA and advanced glycation end product-BSA. (a) Absorbance spectra of native BSA and advanced glycation end product (AGE)-BSA. Samples were incubated with or without glycoaldehyde in PBS, pH 7.2, with equal protein concentrations. (b) Electrophoresis of native BSA and AGE-BSA. Samples were electrophoresed using 10% SDS-PAGE with 4% stacking gel. The gel was run for 1.5 hours at 125 V. The precision plus protein standard (Bio-Rad) served as the molecular size marker. AGE-BSA was derived from the reaction between endotoxin-free BSA (2 mg/ml) and glycoaldehyde (70 mM).