[Preparation of RNAase-free E. coli ribosomes active in initiation of protein biosynthesis]

The level of contaminating RNAases in the main components of the protein biosynthesis initiation system, the initiation factors and ribosomes of E. coli, was studied. It was shown that the ribosomes are the major source of contaminating RNAases. A simple procedure for purification of ribosomes active in initiation including Sephadex G-200 gel-filtration of unwashed ribosomes in a 1.5 M NH4Cl-containing buffer was developed.