Purification and some properties of beet yellows virus

Beet yellows virus was purified by a method, based on ultracentrifuging at 35,000 g, that preserved the normal length of the virus particle and eliminated a uv-absorbing contaminant retained by previously described methods. The purified particles had a modal length in shadowed preparations of 1250 nm and sedimented in the analytical centrifuge usually as one component at 130 S. Purified preparations had an ratio of 1.44 and an extinction coefficient at 260 nm of 2.9. In Cs2SO4 isopycnic banding, the virus had a density of 1.285 g/cm3, while in CsCl two bands were produced at 1.307 and 1.312 g/cm3.