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. 1998 Dec 22;95(26):15598–15602. doi: 10.1073/pnas.95.26.15598

Figure 5.

Figure 5

Gel filtration and mass spectrometric analysis of Aβ peptides released from the apoE–Aβ complex. (a) Dot-blot analysis of the fractions collected after gel filtration of brain soluble preparation immunoprecipitated with the AB947 antibody to apoE from AD and control (CO) subjects. The immunodetection was carried out with the antibodies MAB1062 (to apoE) and αAβ40 (to Aβ40). Both antibodies detected reactive proteins in the high molecular mass region (fractions 1 and 2) as well as in the 30- to 40-kDa region (fractions 6 and 7), the latter co-eluting with human plasma apoE. The antibody αAβ40 detects positive fractions also in the low molecular mass region (fractions 10–12) only in AD preparations; these fractions correspond to the Aβ peptides released from the complex with apoE. (b) After immunoprecipitation with AB947 (to apoE) and gel filtration on a HW50 column the fractions 10–12 from AD and control subjects were analyzed by MALDI-TOF mass spectrometry. The AD samples reveal various carboxyl- and amino-terminally truncated Aβ peptides, whereas in control brains no Aβ peptides are detectable (data not shown). The Aβ peaks are identified by their size in Da, while “m” identifies nonspecific signals due to the matrix.