Identification of Methylated Amino Acids During Sequence Analysis. Application to theEscherichia coliRibosomal Protein L11

Publisher Website
Google Scholar
Abstract
Three methylated amino acid residues, 1 residue of N-trimethylalanine and 2 of N.epsilon.,N.epsilon.,N.epsilon.-trimethyllysine residues, are present in protein L11. The methods used for identification and location of the unusual amino acids in the sequence of protein L11 are described. Temperature and pH modifications to the eluting buffers enabled the detection of the methylated derivatives of lysine and arginine with a Durrum analyzer using routine 90 min amino acid analyses. The presence of N.epsilon.,N.epsilon.-dimethyllysine in the hydrolysate of proteins was revealed by ascending chromatography on thin-layer cellulose plates. The blocked N-terminal amino acid of protein L11, N,N,N-trimethylalanine, although non-volatile, was identified by field desorption mass spectrometry. The identification was confirmed by comparing the N-terminal dipeptide of protein L11 with the synthesized dipeptide Me3Ala-Lys. The behavior of the methylated amino acids during sequence analysis is described.