Figure 7.

Insoluble aggregates formed by reaction of R₅Q₁₈R₅ with brain proteins. Brain proteins (200 μg) incubated overnight with 11.5 milliunits of purified transglutaminase in the presence of 36 μg of R₅Q₁₈R₅ resulted in slow formation of a dense aggregate that settled to the bottom of the tube. Addition of SDS to 1% and 2-mercaptoethanol to 20 mM, followed by heating to 100°C, did not affect the appearance of the aggregate (Center). The aggregate contained 70% of the total initial protein and peptide. A control lacking the peptide (Right) remained completely clear. A second control (Left) containing 100 mM EDTA immediately formed a faint opalescence (not reaction-dependent), but no aggregate at the bottom of the tube. An additional control without brain proteins (not shown) yielded no aggregate.