Ribosomal Proteins

Abstract

All 21 ribosomal proteins from 30 S subunits of Escherichia coli were isolated in a pure state by the following methods: separation of subunits by zonal centrifugation in B X V rotors, extraction of proteins, CM‐cellulose chromatography with pyridine formate gradients, gel filtration on Sephadex G‐100 and, in some cases, preparative polyacrylamide block electrophoresis. The purity of isolated proteins was 97–100% shown by disc electrophoresis at pH 4.5 in urea, by two‐dimensional polyacrylamide electrophoresis, by dodecylsulfate gel electrophoresis and by cellulose acetate gel electrophoresis. The yield of the isolated proteins was 7–110 mg depending on the protein and the number of purification steps. Fractionation of total 30 S proteins with ammonium sulfate is recommended for quick isolation of proteins S15 and S20 in large quantities.