The microenvironment and pKa perturbation of aminoacyl-tRNA guided the selection of cationic amino acids

terminal amine) in Dpr and other non-proteinogenic analogues. The α-selectivity became even poorer in the presence of phosphate, making them ill-suited for peptide synthesis. Superior regioselectivity of the Lys aa-tRNA model substrate suggests that the extra methylene bridge helped nature to separate the microenvironments of the α-amine and ε-amine to synthesize the peptide backbone.