Separation of biological macromolecules in vertical rotors using sucrose gradients shaped by a microprocessor-controlled gradient former.

The separation of macromolecules in vertical rotors using linear or isokinetic sucrose gradients permits shorter centrifugation times and a higher sample capacity compared to swing-out rotors. In vertical rotors appropriate gradients give a resolution almost identical to that in swinging bucket rotors. This could be demonstrated for the isolation of polysomes and oligonucleosomes from rat liver. A microprocessor-controlled gradient former is presented which produces gradients of any desired shape. This device has been applied to prepare gradients with the desired linear or isokinetic shape after reorientation in the vertical tube during centrifugation.