Removal of protein S1 from Escherichia coli ribosomes without the use of affinity chromatography

The paper reports an inexpensive and efficient procedure for the removal of protein S1 from E. coli ribosomes. It comprises incubation of ribosomes in a pyrimidine polyribonucleotide solution followed by centrifugation of the sample through a sucrose cushion. To avoid co-sedimentation of the S1-bound polypyrimidine with the ribosomes, its length should not exceed several hundred nucleotides. Unlike popular affinity chromatography through a poly(U) Sepharose or poly(U) cellulose column, the method tolerates limited polyribonucleotide degradation by eventual traces of ribonucleases, and can readily be incorporated into standard protocols for the isolation of ribosomes by centrifugation. •S1 is removed from ribosomes by centrifugation following incubation with poly(C) or poly(U).•Size matters: Optimally, the pyrimidine polyribonucleotide is 100–200 nt long.•The treatment is compatible with standard ribosome washing procedures.•The expensive affinity resin is no longer needed.