Stability of purified tetramers and high-order oligomers separated by ion-exchanging.

<p>Most of the high-order oligomers were quickly dissociated into tetramers after collection. The purified fractions were concentrated to a protein concentration of 0.3 mg/ml and heated at 80°C or 95°C for a given time. After heat treatment, the samples were analyzed by 10% native-PAGE (upper panel) followed by activity staining (lower panel). A weak band from octomer can be observed when the tetramers were heated at 80°C for 90 min or 95°C for 60 min. TT is tetramer and O is high-order oligomers. The oligomeric size was characterized by the position of the native tetramer as well as the BSA control (data not shown).