The Experimental Research For The Aggregation Of Amloid Beta Peptide Inhibited By Trehalose

As the acceleration of global aging, incidence of people suffering from the Alzheimer's Disease (AD) increases dramatically. At present, AD has become the third most serious disease just after cancer and heart disease. Researchers have confirmed that incidence of AD was due to the aggregation of amyloid beta peptide (Aβ). Being the hydrophobic core of Aβ, Aβ16-22 possesses important research value.This thesis focused both on the aggregations characteristics of the Aβ16-22 oligomers, and the effect of trehalose as an inhibitor on the aggregation of Aβ16-22. Capillary eletrophoresis (CE) was used to analyse the aggregation process of Aβ16-22 in water and trehalose solution; the formation characteristics of the oligomers were observed during the aggregation process. Furthermore, MS spectrum and ultrafilter were also used to identify the production incubated for different time. At the end, transmission electrical microscopy (TEM) was applied to observe the morphology of Aβ16-22 during the process of aggregation. The results were shown as follow.Firstly, capillary eletrophoresis was utilized for detecting the Aβ16-22 oligomer. Since the peptide was found to be highly hydrophobic and had a high isoelectic point, between 10-11, the capillary electrophoresis was operated at relatively low pH ( pH 2.3, 40 mM PBS) in order that a good separation could be achieved.Secondly, through the capillary electrophoresis of Aβ16-22 incubated for different time, the monomer and oligomers were satisfactorily separated with baseline separation. Later on, MS spectrum and ultrafilter were applied to identify the oligomers, and tetramer was found in the mixture.Thirdly, the effect of trehalose on the aggregation of Aβ16-22 was studied. Both the capillary electrophoresis and the TEM images suggested that trehalose could inhibit the aggregation of Aβ16-22. If Aβ16-22 was incubated without trehalsoe, the percentage of the monomer was only 16%, however the percentage of the monomer increased to 70% after incubation with 1 mM trehalose for 3 days, three times more than the former. From the results, it is proved that there is an optimum concentration of trehalose for inhibiting Aβ16-22 aggregration.