Separation and analysis of the soluble trimer of Aβ1–40 and its effects on the rise in intracellular calcium
Separation and analysis of the soluble trimer of Aβ1-40 and its effects on the rise in intracellular calcium

The oligomers of Aβ1–40 peptide in PBS buffer solution were analyzed by SEC and native PAGE, and the trimer of Aβ1–40 was also isolated by SEC. In addition, the effects of the soluble Aβ1–40 trimer on intracellular free calcium (Ca2+) balance of hippocampal neurons of postnatal rats were investigated by fluorescence microscopy. The experimental results indicated that Aβ1–40 peptide existed in the form of low molecular weight oligomers in 0.231 mmol/L fresh Aβ1–40 solution (20 mmol/L sodium phosphate buffer, pH 7.4, 0.02% sodium azide) within 24 h and the soluble trimer was the most abundant species. Both the trimeric and the fibrillar Aβ1–40 were able to increase the intracellular Ca2+ concentration, but the Aβ1–40 trimer caused a gradual rise and the potential was also stronger than that of the fibrils at the same concentration. In addition there were different response modes for trimeric and fibrillar Aβ1–40, meaning that there are different mechanisms of increase in intracellular Ca2+ caused by Aβ1–40.