RIBOSOMAL PROTEINS OF ESCHERICHIA COLI .I. PURIFICATION OF 30S RIBOSOMAL PROTEINS

The proteins of the 30S ribosomal subunit of Escherichia coli were separated from the ribosomal ribonucleic acid by a modification of the standard acetic acid extraction procedure. Chromatography of the proteins on cellulose phosphate columns led to the identification of approximately 20 unique protein fractions. Rechromatography of these proteins either on cellulose phosphate or Sephadex columns yielded 21 proteins that were chromatographically and electrophoretically unique. Control experiments suggest that these proteins are not artifacts produced by disulfide bond aggregation, noncovalent aggregation, enzymatic fragmentation, or supernatant contamination. It is concluded that there are approximately 20 proteins in the 30S subunit of E. coli. © 1969, American Chemical Society. All rights reserved.