Studies in Ageing of the Brain: I. Isolation and Preliminary Characterization of Alzheimer Plaques and Cores

In this study Alzheimer plaques and their central cores were isolated and analyzed. Temporal lobe cortex was homogenized, centrifuged, and fractionated on a sucrose density gradient. Scanning electron micrographs of the amyloid-like cores were reminiscent of a tissue paper flower or of a sea sponge. Infrared studies of plaques and cores showed evidence consistent with a polyamide (protein-like) structure with small amounts of carbohydrates present. Amino acids predominating in the plaques were glutamic acid, glycine, leucine, and alanine. Amino acids predominating in the cores were glycine, glutamic acid, aspartic acid, serine, and leucine. Electron probe microanalyses showed that plaques without cores and cores per se contained phosphorus and sulfur (>1%).