Fig. 3.

Electron micrographs of negatively stained total plasma LDL at various stages of thermal denaturation. Aliquots were taken at different times of incubation at 85°C as described in Fig. 2. Panel numbers correspond to the denaturation stages in Fig. 2. Each aliquot was cooled to 22°C, diluted to 50 μg/ml protein, and visualized by negative-staining EM. Intact LDL (not shown) and LDL that had been incubated at 85°C for 4 min (2) or less were indistinguishable by EM; other micrographs show LDL that have been incubated at 85°C for 6 min (3), 12 min (6), 17 min (7), or 24 min (8). Short white arrows point to fused LDL, black arrows to particles that are smaller than intact LDL, and long white arrows to electrolucent strands whose morphology is consistent with dissociated apoB.