Alzheimer's peptides Aβ1-40 and Aβ1-28 inhibit the plasma cholesterol esterification rate

The amyloid fibrils of Alzheimer's disease and Down's syndrome amyloid deposits are composed mainly of aggregated amyloid beta protein (Aβ) which also exists in a soluble form. It has been shown that both Alzheimer's disease and Down's syndrome share another common feature: the decrease in plasma cholesterol esterification in affected individuals. In the present work the effect of synthetic peptides Aβ1-40 and Aβ1-28 on normal human plasma cholesterol esterification rate was studied. Both peptides at a concentration of 1 ng/ml inhibited plasma cholesterol esterification rate to 40-50% of control value. Statistical analysis showed no differences in the effect of Aβ1-40 and Aβ1-28 on the inhibition, suggesting the importance of Aβ sequence 1-28 for this effect.