The requirement for the protonated α-amino group for the transport of peptides in Escherichia coli

Abstract

Many glycine peptides support growth of a glycine auxotroph of Escherichia coli. If the α-amino group of these peptides is methylated, the products are still utilized for growth, and also retain comparable ability with the unsubstituted peptides to compete with natural peptides for transport into the cell. In contrast, glycine peptides devoid of an α-amino group, or that have the α-amino group substituted by one of a number of acyl groups are not utilized, although E. coli possesses intracellular enzymic activity able to release glycine from such compounds; further, these derivatives do not compete with natural peptides for transport into the cell.