title: Characterization of methylated neutral amino acids from Escherichia coli ribosomes.
abstract: The methylated neutral amino acids from both 30S and 50S ribosomal subunits of an Escherichia coli K strain were characterized. The 50S ribosomal subunit contains three methylated neutral amino acids: N-monomethylalanine, N-monomethylmethionine, and an as yet unidentified methylated amino acid found in protein L11. Both N-monomethylalanine and N-monomethylmethionine were found in protein L33. The amount of N-monomethylmethionine in this protein, however, is variable but not more than 0.25 molecules per protein. Thus protein L33 from this E. coli K strain has heterogeneity in its N-terminal amino acid and can start with either N-monomethylalanine or N-monomethylmethionine. The N-monomethylmethionine residue was not derived from the reduction of N-formylmethionine in the protein. The 30S ribosomal subunit contains only one methylated neutral amino acid: N-monomethylalanine.
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives* / Q000032:analysis; D001426:Bacterial Proteins / Q000032:analysis*; D004926:Escherichia coli / Q000032:analysis* / Q000378:metabolism; D008715:Methionine / Q000031:analogs & derivatives* / Q000032:analysis; D008745:Methylation; D009239:N-Formylmethionine / Q000378:metabolism; D012269:Ribosomal Proteins / Q000032:analysis*
chemical_list: D001426:Bacterial Proteins; D012269:Ribosomal Proteins; D009239:N-Formylmethionine; D008715:Methionine; D000409:Alanine