MEMBRANE INSERTION OF Aβ WOULD INDUCE ITS FIBRIL FORMATION
淀粉样蛋白Aβ的插膜作用可以抑制其形成纤维

a-Amyloid peptide (A a ), the core protein of amyloid plaques in Alzheimer's disease, is a mixture of multilength peptides which are all derived from the amyloid precursor protei n (APP), and A a 40 and A a 42 are the two major components of the mixture. The effects of me mbrane cholesterol and buffer pH on the fibril formation of A a 40 and A a 42 were investigated respectively in this paper. The observation of electronic microscopy showed that cholesterol-containing liposome could nearl y completely inhibit the fibril formation of A a 40, and low pH could partly inhibit the fibrils formation of A a 42. Monolayer approach showed that A a 40 and A a 42 both were inclined to insert into membrane under the two above conditions. Further conformational measurements showed that the membrane in sertion had different effects on the secondary structure of A a 40 and A a 42. Therefore, the results of this paper indicate that the mechanisms to inh ibit the fibril formation of the two proteins are different, while the membrane insertion of A a 40 or A a 42 can reduce the fibril formation to a certain extent.