2.3 Capsid protein (CP) purification
The native BMV virions were disassembled to obtain the CP protein needed
to synthesize the VLPs. First, the BMV virions were dialyzed against the
disassembly buffer (0.5 M CaCl2, 50 mM Tris-HCl, pH 7.4)
for 5 h. Then, the resulting disassembled CP was centrifuged at 50,000
rpm, 4°C for 4 h. After centrifugation, the supernatant containing the
CP was collected in 0.5 mL fractions. The CP purity of the fractions was
estimated using the A280/A260 nm
quotient. The best fractions (A280/A260≥ 1.6) were combined and dialyzed against the protein buffer (1 M NaCl,
20 mM Tris-HCl, pH 7.2) for 2 h. Finally, the dialyzed CP was recovered
and then quantified by absorbance using the CP extinction coefficient.