Overview of Alzheimer’s Disease and Some Therapeutic Approaches Targeting Aβ by Using Several Synthetic and Herbal Compounds

Figure 4

A model showing oligomerization and fibrillization: the equilibrium between monomer to paranuclei and from paranuclei to large oligomers is rapid and reversible. The conversion of oligomers to protofibrils is slower but also reversible. Conversion of protofibrils into fibrils is an irreversible step. Basically, the monomers, paranuclei, and large oligomers do not have any definite structure instead of some β-turn/β-sheet and helical (α) elements. Essential conformational changes occur during protofibril formation where the unstructured, α-helix, and β-strand elements transform into β-sheet/β-turn structures.