FIG. 4.

Ten to 65% linear sucrose gradient analysis of HPV-11 VLPs in various states of assembly. An aliquot of purified VLP starting material (a) was incubated with 5% βME for 16 h at 4°C (b). A portion of βME-treated VLPs were then reassembled by dialysis into PBS–0.5 NaCl to remove reducing agent (c). The samples were then centrifuged on 10 to 65% linear sucrose gradients as described in the text. Each gradient was collected in 12 fractions (1 ml), and the pellet (P) was resuspended in 1 ml of PBS. Shown are immunoblots demonstrating the positions at which the L1 protein migrated on the different gradients. Also indicated are the peak positions at which sedimentation standards migrated, as in Fig. 3.