Peptide analyses of a protein component, 50-8, of 50s ribosomal subunit from erythromycin resistant mutants of Escherichia coli and Escherichia freudii

Summary Chromatographic analyses on a Dowex 50x8 column of tryptic digests of the mutationally altered 50-8 protein component from several erythromycin resistant (ery^r) mutants of Escherichia coli and Escherichia freundii have been performed. It was found that (1) the difference in the elution profile of the altered components detected with carboxymethyl cellulose column chromatography reflects the difference in their amino acid sequence, (2) the structural change(s) of the 50-8 protein from three E. coli ery^r mutants examined seems to exist only in the same single peptide fragment and (3) the primary structure of the 50-8(R) protein of E. freundii (ery^s: wild type) differs from that of E. coli Q13 (ery^s) and the structural change in 50-8(R) component of E. freundii caused by the ery^r mutation was found to take place in different peptide fragments from that in which the mutational change of the E. coli 50-8 component occurred.