Fig. 3.
Conformational-stability assays of synthetic prions on second passage in Tg9949 mice. Brain homogenates from one Tg9949 mouse (MK4977) that showed signs of neurologic dysfunction at 379 days after inoculation with synthetic prions were inoculated into two other Tg9949 mice. (A and C) Western blots of PrPSc in brain extracts of mouse MM6055 that was killed after developing signs of neurologic dysfunction at 204 days after inoculation (A) and mouse MM6060 that showed signs of neurologic dysfunction at 270 days after inoculation (C). Lanes 0–6, samples were exposed to increasing concentrations of GdnHCl (0–6 M, as indicated), then subjected to digestion with 20 μg/ml PK for 1 h at 37°C. Lane C, undigested control sample that was not exposed to Gdn·HCl. Molecular weight markers based on the migration of protein standards are indicated in kilodaltons. (B and D) Denaturation curves obtained by scanning the PrP 27–30 signals in the Western blots shown in A and C, respectively, show the [Gdn·HCl]1/2 values.