Figure 3.

Chromatographic patterns of crude brain and cerebrovascular proteins separated by Superose 12 FPLC from immunized individuals with the AN-1792 antigen. The collected proteins, spanning the molecular masses from 2 to 8 kd, are indicated by the horizontal bar. The Superose 12 columns were calibrated using monomeric and dimeric Aβ. A: Leptomeningeal vessels. The vascular amyloid is very abundant in the walls of leptomeningeal arteries (Figure 2E), where it represents the most abundant protein. B: A pure preparation of cortical vessels extracted with GDFA. The Aβ peptide-containing fraction is highly enriched by the FPLC step. C: Cerebral cortex water-soluble proteins obtained after gentle homogenization of the brain tissue and high-speed ultracentrifugation. The lyophilized supernatant was dissolved in GDFA and submitted to FPLC. To increase the yield and eliminate contaminating flanking proteins, with higher and lower molecular masses, the fractions eluted within the 2- to 8-kd portion (trace a) were concentrated and re-chromatographed (trace b). D: The vascular depleted cerebral cortex SDS-insoluble/formic acid-soluble Aβ peptides were separated by FPLC (trace a). To further enrich the Aβ peptides, the specimens were re-chromatographed under the same conditions (trace b). E: The FPLC profile of the WM GDFA-soluble proteins. To enhance the purification of the Aβ peptides (trace a), the 2- to 8-kd fractions from four FPLC runs were pooled, concentrated, and re-chromatographed (trace b).