Alzheimer’s is an ugly disease.  But, I dare say the picture here of the protein that is associated with the massive loss of neurons in the brain of Alzheimer’s patients is actually rather cool looking.

The fibrils consist of a protein fragment called amyloid-beta 1-40, an insoluble forty amino acid polypeptide generated by the sequential actions of a number of enzymes on the amyloid precursor protein (APP). These fragments polymerize (or join end-to-end) and are deposited in the spaces around neurons; the deposits (plaques) are toxic, and are widely believed to be responsible for the loss of cells that occurs in Alzheimer’s. However, this has not yet been determined – the plaques could be an effect, rather than the cause, of neurodegeneration.