Analytical techniques for cell fractions: V. Characteristics of the B-XIV and B-XV zonal centrifuge rotors☆

Zonal centrifuges,3 developed for the mass separation of subcellular particles and viruses on the basis of either sedimentation rate or buoyant density (l-8)) have been used to isolate the major subcellular components (7), viruses (4, 5, 9, lo), ribosomal RNA (ll), and serum macroglobulins (12). An advantage of the B-IV tonal rotor previously described (6, 13) is that it may be easily converted into a high-speed continuous-flow centrifuge with (14) or without (15) isopycnic banding during operation. A disadvantage of this rotor is that a special centrifuge with extended armor, a cooled upper bearing, and a high-speed seal are required. Where continuous-flow centrifugation capability is not needed, a much simpler rotor with a removable seal which can be spun in un-