| Beta amyloid 1-42 is known as a biomarker of Alzheimer's disease. Amyloid is detectable in cerebrospinal fluid (CSF). It is a 42-amino acid fragment of amyloid precursor protein. The peptide is well suited for use as a standard in the quantitation of Alzheimer's. Beta amyloid (12–28) residues are the binding site for apolipoprotein E (apoE) on Beta amyloid. This sequence encompasses a hydrophobic domain (residues 14–21) and a beta-turn (residues 22–28) which place two hydrophobic domains of Beta amyloid 14 to 21 and 29 to 40/42 opposite each other, allowing for the assembly of Beta amyloid peptides into fibrils. The secondary structure of Beta amyloid (12- 28), a neutral peptide, is dominated by a-helix and random coil. The interaction of apoE with residues 12 to 28 of Beta amyloid is not just a non-specific hydrophobic interaction but plays a pivotal role in the mechanism of Aß pathology in Alzheimer’s disease (AD). Beta amyloid (11-28) and five other fragments enhanced aggregation of full length Beta amyloid (1-40). All of the peptides that enhance aggregation contained either residues 17 to 20 or 30 to 35, indicating the importance of these regions for promoting aggregation of full-length Beta amyloid. Injection of the amyloid beta-protein fragment VHHQKLVFFAEDVGSNK into different limbic system structures in mice impaired retention with remarkably similar efficacy and in a dose-dependent manner. Beta amyloid (12-28) and other Beta amyloid fragments may exert dysregulatory cognitive effects by incoordination of K? channel function in neurons, glia and endothelial cells. |
