A detergent-free method for isolation of viable ribosomes from rat brain

A detergent-free method based on sucrose density gradient centrifugations was developed for isolation of free ribosomes from rat brain. The purity of the preparations was checked by RNA/protein ratio, electron microscopy and marker enzymes. They were uncontaminated by other cell organelles. The incorporation of leucine, isoleucine and valine into acid-insoluble fraction by ribosomes comformed to the Hill equation v/V = sn/(K+sn). Branched-chain amino acids mutually inhibited each other's incorporation by ribosomes, but the inhibition was abolished with detergents frequently used in isolation procedures.