CMR studies of protein modification. Progressive decrease in charge density at the ε-amino function of lysine with increasing methyl substitution

Abstract

Progressive methyl substitution at the ε-amino group of lysine results in a progressive downfield shift of the signals from the ε and N -methyl carbon atoms in the Carbon-13 nmr spectra of the resulting ε- N -methylated lysine derivatives. The results are consistent with the view that the greater the number of ε, N -methyl groups on protein basic aminoacid residues, the greater the affinity of these residues for anionic species, e.g. as in histone-DNA interactions.