The important enzyme, beta-secretase is pictured.  It is bound to the surface of a 
neuronal cell membrane and is shown cleaving the amyloid precursor protein (APP) to 
form amyloid beta.  Amyloid beta formation leads to plaque in the brains 
of Alzheimer's patients. A drug that would inhibit beta-secretase would inhibit plaque 
formation and effectively treat Alzheimer's disease.